diff --git a/binding-sandbox/audio-binding.h b/binding-sandbox/audio-binding.h
index a60c6fee..092dd403 100644
--- a/binding-sandbox/audio-binding.h
+++ b/binding-sandbox/audio-binding.h
@@ -28,9 +28,9 @@
 namespace mkxp_sandbox {
     static VALUE audio_module;
 
-    SANDBOX_COROUTINE(audio_binding_init,
+    struct audio_binding_init : boost::asio::coroutine {
         static VALUE bgm_play(int32_t argc, wasm_ptr_t argv, VALUE self) {
-            SANDBOX_COROUTINE(coro,
+            struct coro : boost::asio::coroutine {
                 wasm_ptr_t filename;
                 int32_t volume;
                 int32_t pitch;
@@ -69,7 +69,7 @@ namespace mkxp_sandbox {
 
                     return SANDBOX_NIL;
                 }
-            )
+            };
 
             return sb()->bind<struct coro>()()(argc, argv, self);
         }
@@ -80,7 +80,7 @@ namespace mkxp_sandbox {
         }
 
         static VALUE bgm_fade(int32_t argc, wasm_ptr_t argv, VALUE self) {
-            SANDBOX_COROUTINE(coro,
+            struct coro : boost::asio::coroutine {
                 int32_t time;
                 int32_t track;
 
@@ -96,13 +96,13 @@ namespace mkxp_sandbox {
 
                     return SANDBOX_NIL;
                 }
-            )
+            };
 
             return sb()->bind<struct coro>()()(argc, argv, self);
         }
 
         static VALUE bgm_pos(int32_t argc, wasm_ptr_t argv, VALUE self) {
-            SANDBOX_COROUTINE(coro,
+            struct coro : boost::asio::coroutine {
                 int32_t track;
                 double pos;
                 VALUE value;
@@ -119,13 +119,13 @@ namespace mkxp_sandbox {
 
                     return value;
                 }
-            )
+            };
 
             return sb()->bind<struct coro>()()(argc, argv, self);
         }
 
         static VALUE bgm_volume(int32_t argc, wasm_ptr_t argv, VALUE self) {
-            SANDBOX_COROUTINE(coro,
+            struct coro : boost::asio::coroutine {
                 int32_t track;
                 int32_t volume;
                 VALUE value;
@@ -142,13 +142,13 @@ namespace mkxp_sandbox {
 
                     return value;
                 }
-            )
+            };
 
             return sb()->bind<struct coro>()()(argc, argv, self);
         }
 
         static VALUE bgm_set_volume(int32_t argc, wasm_ptr_t argv, VALUE self) {
-            SANDBOX_COROUTINE(coro,
+            struct coro : boost::asio::coroutine {
                 int32_t volume;
                 int32_t track;
 
@@ -164,13 +164,13 @@ namespace mkxp_sandbox {
 
                     return SANDBOX_NIL;
                 }
-            )
+            };
 
             return sb()->bind<struct coro>()()(argc, argv, self);
         }
 
         static VALUE bgs_play(int32_t argc, wasm_ptr_t argv, VALUE self) {
-            SANDBOX_COROUTINE(coro,
+            struct coro : boost::asio::coroutine {
                 wasm_ptr_t filename;
                 int32_t volume;
                 int32_t pitch;
@@ -198,7 +198,7 @@ namespace mkxp_sandbox {
 
                     return SANDBOX_NIL;
                 }
-            )
+            };
 
             return sb()->bind<struct coro>()()(argc, argv, self);
         }
@@ -209,7 +209,7 @@ namespace mkxp_sandbox {
         }
 
         static VALUE bgs_fade(VALUE self, VALUE value) {
-            SANDBOX_COROUTINE(coro,
+            struct coro : boost::asio::coroutine {
                 int32_t time;
 
                 VALUE operator()(VALUE self, VALUE value) {
@@ -220,13 +220,13 @@ namespace mkxp_sandbox {
 
                     return SANDBOX_NIL;
                 }
-            )
+            };
 
             return sb()->bind<struct coro>()()(self, value);
         }
 
         static VALUE bgs_pos(VALUE self) {
-            SANDBOX_COROUTINE(coro,
+            struct coro : boost::asio::coroutine {
                 double pos;
                 VALUE value;
 
@@ -238,13 +238,13 @@ namespace mkxp_sandbox {
 
                     return value;
                 }
-            )
+            };
 
             return sb()->bind<struct coro>()()(self);
         }
 
         static VALUE me_play(int32_t argc, wasm_ptr_t argv, VALUE self) {
-            SANDBOX_COROUTINE(coro,
+            struct coro : boost::asio::coroutine {
                 wasm_ptr_t filename;
                 int32_t volume;
                 int32_t pitch;
@@ -267,7 +267,7 @@ namespace mkxp_sandbox {
 
                     return SANDBOX_NIL;
                 }
-            )
+            };
 
             return sb()->bind<struct coro>()()(argc, argv, self);
         }
@@ -278,7 +278,7 @@ namespace mkxp_sandbox {
         }
 
         static VALUE me_fade(VALUE self, VALUE value) {
-            SANDBOX_COROUTINE(coro,
+            struct coro : boost::asio::coroutine {
                 int32_t time;
 
                 VALUE operator()(VALUE self, VALUE value) {
@@ -289,13 +289,13 @@ namespace mkxp_sandbox {
 
                     return SANDBOX_NIL;
                 }
-            )
+            };
 
             return sb()->bind<struct coro>()()(self, value);
         }
 
         static VALUE se_play(int32_t argc, wasm_ptr_t argv, VALUE self) {
-            SANDBOX_COROUTINE(coro,
+            struct coro : boost::asio::coroutine {
                 wasm_ptr_t filename;
                 int32_t volume;
                 int32_t pitch;
@@ -318,7 +318,7 @@ namespace mkxp_sandbox {
 
                     return SANDBOX_NIL;
                 }
-            )
+            };
 
             return sb()->bind<struct coro>()()(argc, argv, self);
         }
@@ -360,7 +360,7 @@ namespace mkxp_sandbox {
                 SANDBOX_AWAIT(rb_define_module_function, audio_module, "__reset__", (VALUE (*)(ANYARGS))reset, 0);
             }
         }
-    )
+    };
 }
 
 #endif // MKXPZ_SANDBOX_AUDIO_BINDING_H
diff --git a/binding-sandbox/binding-base.h b/binding-sandbox/binding-base.h
index a930f181..dc1b6013 100644
--- a/binding-sandbox/binding-base.h
+++ b/binding-sandbox/binding-base.h
@@ -26,9 +26,11 @@
 #include <cstdint>
 #include <cstring>
 #include <memory>
+#include <type_traits>
 #include <unordered_map>
 #include <utility>
 #include <vector>
+#include <boost/core/enable_if.hpp>
 #include <boost/container_hash/hash.hpp>
 #include <boost/asio/coroutine.hpp>
 #include <mkxp-retro-ruby.h>
@@ -122,7 +124,15 @@ namespace mkxp_sandbox {
                 return bind.fibers[key];
             }
 
-            static wasm_ptr_t init_inner(struct binding_base &bind, struct fiber &fiber) {
+            template <typename U> static typename boost::enable_if<std::is_constructible<U, struct binding_base &>, void>::type construct_frame_at(void *ptr, struct binding_base &bind) {
+                new(ptr) U(bind);
+            }
+
+            template <typename U> static typename boost::disable_if<std::is_constructible<U, struct binding_base &>, void>::type construct_frame_at(void *ptr, struct binding_base &bind) {
+                new(ptr) U;
+            }
+
+            static wasm_ptr_t init_frame(struct binding_base &bind, struct fiber &fiber) {
                 uint32_t state = w2c_ruby_asyncify_get_state(&bind.instance());
 
                 if (fiber.stack_ptr > fiber.stack.size()) {
@@ -151,12 +161,12 @@ namespace mkxp_sandbox {
                 );
                 assert(sp % sizeof(VALUE) == 0);
                 assert(sp % WASMSTACKALIGN == 0);
-                new(*bind + sp) T(bind);
+                construct_frame_at<T>(*bind + sp, bind);
                 w2c_ruby_rb_wasm_set_stack_pointer(&bind.instance(), sp);
                 return sp;
             }
 
-            stack_frame_guard(struct binding_base &b) : bind(&b), fiber(&init_fiber(b)), ptr(init_inner(b, *fiber)) {}
+            stack_frame_guard(struct binding_base &b) : bind(&b), fiber(&init_fiber(b)), ptr(init_frame(b, *fiber)) {}
 
         public:
             stack_frame_guard(const stack_frame_guard &frame) = delete;
diff --git a/binding-sandbox/binding-sandbox.h b/binding-sandbox/binding-sandbox.h
index 20bd6e69..056888ec 100644
--- a/binding-sandbox/binding-sandbox.h
+++ b/binding-sandbox/binding-sandbox.h
@@ -47,10 +47,10 @@ extern const char module_rpg3[];
 
 namespace mkxp_sandbox {
     // Evaluates a script, returning the exception if it encountered an exception or `SANDBOX_UNDEF` otherwise.
-    SANDBOX_COROUTINE(eval_script,
+    struct eval_script : boost::asio::coroutine {
         private:
         static VALUE func(VALUE arg) {
-            SANDBOX_COROUTINE(coro,
+            struct coro : boost::asio::coroutine {
                 VALUE string;
                 VALUE filename;
                 ID id;
@@ -63,18 +63,18 @@ namespace mkxp_sandbox {
                         SANDBOX_AWAIT(rb_funcall, SANDBOX_NIL, id, 3, string, SANDBOX_NIL, filename);
                     }
                 }
-            )
+            };
 
             sb()->bind<struct coro>()()(arg);
             return SANDBOX_UNDEF;
         }
 
         static VALUE rescue(VALUE arg, VALUE exception) {
-            SANDBOX_COROUTINE(coro,
+            struct coro : boost::asio::coroutine {
                 VALUE operator()(VALUE exception) {
                     return exception;
                 }
-            )
+            };
 
             return sb()->bind<struct coro>()()(exception);
         }
@@ -92,10 +92,10 @@ namespace mkxp_sandbox {
 
             return value;
         }
-    )
+    };
 
     // Runs the game scripts.
-    SANDBOX_COROUTINE(run_rmxp_scripts,
+    struct run_rmxp_scripts : boost::asio::coroutine {
         VALUE value;
         VALUE scripts;
         wasm_size_t script_count;
@@ -225,11 +225,11 @@ namespace mkxp_sandbox {
                 std::free(decode_buffer);
             }
         }
-    )
+    };
 
-    SANDBOX_COROUTINE(sandbox_binding_init,
+    struct sandbox_binding_init : boost::asio::coroutine {
         static VALUE load_data(VALUE self, VALUE path) {
-            SANDBOX_COROUTINE(coro,
+            struct coro : boost::asio::coroutine {
                 VALUE value;
                 VALUE file;
                 wasm_ptr_t ptr;
@@ -254,15 +254,15 @@ namespace mkxp_sandbox {
                         delete path_str;
                     }
                 }
-            )
+            };
 
             return sb()->bind<struct coro>()()(path);
         }
 
         static VALUE rgss_main(VALUE self) {
-            SANDBOX_COROUTINE(coro,
+            struct coro : boost::asio::coroutine {
                 static VALUE func(VALUE block) {
-                    SANDBOX_COROUTINE(coro,
+                    struct coro : boost::asio::coroutine {
                         ID id;
 
                         VALUE operator()(VALUE block) {
@@ -273,7 +273,7 @@ namespace mkxp_sandbox {
 
                             return SANDBOX_UNDEF;
                         }
-                    )
+                    };
 
                     return sb()->bind<struct coro>()()(block);
                 }
@@ -297,13 +297,13 @@ namespace mkxp_sandbox {
 
                     return SANDBOX_NIL;
                 }
-            )
+            };
 
             return sb()->bind<struct coro>()()(self);
         }
 
         static VALUE rgss_stop(VALUE self) {
-            SANDBOX_COROUTINE(coro,
+            struct coro : boost::asio::coroutine {
                 VALUE operator()(VALUE self) {
                     BOOST_ASIO_CORO_REENTER (this) {
                         while (true) {
@@ -313,7 +313,7 @@ namespace mkxp_sandbox {
 
                     return SANDBOX_NIL;
                 }
-            )
+            };
 
             return sb()->bind<struct coro>()()(self);
         }
@@ -360,7 +360,7 @@ namespace mkxp_sandbox {
                 SANDBOX_AWAIT(run_rmxp_scripts);
             }
         }
-    )
+    };
 }
 
 #endif // MKXPZ_BINDING_SANDBOX_H
diff --git a/binding-sandbox/binding-util.h b/binding-sandbox/binding-util.h
index 0716aa34..dbef947d 100644
--- a/binding-sandbox/binding-util.h
+++ b/binding-sandbox/binding-util.h
@@ -29,42 +29,46 @@
 
 #define SANDBOX_DEF_ALLOC(rbtype) \
     static VALUE alloc(VALUE _klass) { \
-        SANDBOX_COROUTINE(alloc, \
+        using namespace ::mkxp_sandbox; \
+        struct coro : boost::asio::coroutine { \
             VALUE _obj; \
             VALUE operator()(VALUE _klass) { \
                 BOOST_ASIO_CORO_REENTER (this) { \
-                    SANDBOX_AWAIT_AND_SET(_obj, mkxp_sandbox::rb_data_typed_object_wrap, _klass, 0, rbtype); \
+                    SANDBOX_AWAIT_AND_SET(_obj, rb_data_typed_object_wrap, _klass, 0, rbtype); \
                 } \
                 return _obj; \
             } \
-        ) \
-        return mkxp_sandbox::sb()->bind<struct alloc>()()(_klass); \
+        }; \
+        return sb()->bind<struct coro>()()(_klass); \
     }
 
 #define SANDBOX_DEF_ALLOC_WITH_INIT(rbtype, initializer) \
     static VALUE alloc(VALUE _klass) { \
-        SANDBOX_COROUTINE(alloc, \
+        using namespace ::mkxp_sandbox; \
+        struct coro : boost::asio::coroutine { \
             VALUE _obj; \
             VALUE operator()(VALUE _klass) { \
                 BOOST_ASIO_CORO_REENTER (this) { \
-                    SANDBOX_AWAIT_AND_SET(_obj, mkxp_sandbox::rb_data_typed_object_wrap, _klass, 0, rbtype); \
-                    mkxp_sandbox::set_private_data(_obj, initializer); /* TODO: free when sandbox is deallocated */ \
+                    SANDBOX_AWAIT_AND_SET(_obj, rb_data_typed_object_wrap, _klass, 0, rbtype); \
+                    set_private_data(_obj, initializer); /* TODO: free when sandbox is deallocated */ \
                 } \
                 return _obj; \
             } \
-        ) \
-        return mkxp_sandbox::sb()->bind<struct alloc>()()(_klass); \
+        }; \
+        return sb()->bind<struct coro>()()(_klass); \
     }
 
 #define SANDBOX_DEF_DFREE(T) \
     static void dfree(wasm_ptr_t _buf) { \
-        delete *(T **)(**mkxp_sandbox::sb() + _buf); \
-        mkxp_sandbox::sb()->sandbox_free(_buf); \
+        using namespace ::mkxp_sandbox; \
+        delete *(T **)(**sb() + _buf); \
+        sb()->sandbox_free(_buf); \
     }
 
 #define SANDBOX_DEF_LOAD(T) \
     static VALUE load(VALUE _self, VALUE _serialized) { \
-        SANDBOX_COROUTINE(load, \
+        using namespace ::mkxp_sandbox; \
+        struct coro : boost::asio::coroutine { \
             VALUE _obj; \
             wasm_ptr_t _ptr; \
             wasm_size_t _len; \
@@ -73,19 +77,21 @@
                     SANDBOX_AWAIT_AND_SET(_obj, rb_obj_alloc, _self); \
                     SANDBOX_AWAIT_AND_SET(_ptr, rb_string_value_ptr, &_serialized); \
                     SANDBOX_AWAIT_AND_SET(_len, get_bytesize, _serialized); \
-                    set_private_data(_obj, T::deserialize((const char *)(**mkxp_sandbox::sb() + _ptr), _len)); /* TODO: free when sandbox is deallocated */ \
+                    set_private_data(_obj, T::deserialize((const char *)(**sb() + _ptr), _len)); /* TODO: free when sandbox is deallocated */ \
                 } \
                 return _obj; \
             } \
-        ) \
-        return mkxp_sandbox::sb()->bind<struct load>()()(_self, _serialized); \
+        }; \
+        return sb()->bind<struct coro>()()(_self, _serialized); \
     }
 
 #define SANDBOX_DEF_CLASS_PROP_B(S, prop, name) \
     static VALUE get_##name(VALUE self) { \
+        using namespace ::mkxp_sandbox; \
         return SANDBOX_BOOL_TO_VALUE(S::get##prop()); \
     } \
     static VALUE set_##name(VALUE self, VALUE value) { \
+        using namespace ::mkxp_sandbox; \
         bool v = SANDBOX_VALUE_TO_BOOL(value); \
         S::set##prop(v); \
         return value; \
@@ -93,10 +99,12 @@
 
 #define SANDBOX_DEF_CLASS_PROP(V, num2val, val2num, S, prop, name) \
     static VALUE get_##name(VALUE self) { \
-        return mkxp_sandbox::sb()->bind<struct num2val>()()(S::get##prop()); \
+        using namespace ::mkxp_sandbox; \
+        return sb()->bind<struct num2val>()()(S::get##prop()); \
     } \
     static VALUE set_##name(VALUE self, VALUE value) { \
-        SANDBOX_COROUTINE(coro, \
+        using namespace ::mkxp_sandbox; \
+        struct coro : boost::asio::coroutine { \
             VALUE operator()(VALUE self, VALUE value) { \
                 V v; \
                 BOOST_ASIO_CORO_REENTER (this) { \
@@ -105,8 +113,8 @@
                 } \
                 return value; \
             } \
-        ) \
-        return mkxp_sandbox::sb()->bind<struct coro>()()(self, value); \
+        }; \
+        return sb()->bind<struct coro>()()(self, value); \
     }
 
 #define SANDBOX_DEF_CLASS_PROP_I(S, prop, name) SANDBOX_DEF_CLASS_PROP(int32_t, rb_ll2inum, rb_num2int, S, prop, name)
@@ -115,10 +123,12 @@
 
 #define SANDBOX_DEF_CLASS_PROP_OBJ_REF(S, V, prop, name) \
     static VALUE get_##name(VALUE self) { \
-        return mkxp_sandbox::sb()->bind<struct rb_iv_get>()()(self, #name); \
+        using namespace ::mkxp_sandbox; \
+        return sb()->bind<struct rb_iv_get>()()(self, #name); \
     } \
     static VALUE set_##name(VALUE self, VALUE value) { \
-        SANDBOX_COROUTINE(coro, \
+        using namespace ::mkxp_sandbox; \
+        struct coro : boost::asio::coroutine { \
             VALUE operator()(VALUE self, VALUE value) { \
                 BOOST_ASIO_CORO_REENTER (this) { \
                     { \
@@ -129,15 +139,17 @@
                 } \
                 return value; \
             } \
-        ) \
-        return mkxp_sandbox::sb()->bind<struct coro>()()(self, value); \
+        }; \
+        return sb()->bind<struct coro>()()(self, value); \
     }
 
 #define SANDBOX_DEF_CLASS_PROP_OBJ_VAL(S, V, prop, name) \
     static VALUE get_##name(VALUE self) { \
-        return mkxp_sandbox::sb()->bind<struct rb_iv_get>()()(self, #name); \
+        using namespace ::mkxp_sandbox; \
+        return sb()->bind<struct rb_iv_get>()()(self, #name); \
     } \
     static VALUE set_##name(VALUE self, VALUE value) { \
+        using namespace ::mkxp_sandbox; \
         V *v = get_private_data<V>(value); \
         S::set##prop(*v); \
         return value; \
@@ -145,10 +157,12 @@
 
 #define SANDBOX_DEF_PROP_B(S, prop, name) \
     static VALUE get_##name(VALUE self) { \
+        using namespace ::mkxp_sandbox; \
         S *s = get_private_data<S>(self); \
         return SANDBOX_BOOL_TO_VALUE(s->get##prop()); \
     } \
     static VALUE set_##name(VALUE self, VALUE value) { \
+        using namespace ::mkxp_sandbox; \
         S *s = get_private_data<S>(self); \
         bool v = SANDBOX_VALUE_TO_BOOL(value); \
         s->set##prop(v); \
@@ -157,10 +171,12 @@
 
 #define SANDBOX_DEF_PROP(V, num2val, val2num, S, prop, name) \
     static VALUE get_##name(VALUE self) { \
-        return mkxp_sandbox::sb()->bind<struct num2val>()()(get_private_data<S>(self)->get##prop()); \
+        using namespace ::mkxp_sandbox; \
+        return sb()->bind<struct num2val>()()(get_private_data<S>(self)->get##prop()); \
     } \
     static VALUE set_##name(VALUE self, VALUE value) { \
-        SANDBOX_COROUTINE(coro, \
+        using namespace ::mkxp_sandbox; \
+        struct coro : boost::asio::coroutine { \
             VALUE operator()(VALUE self, VALUE value) { \
                 V v; \
                 BOOST_ASIO_CORO_REENTER (this) { \
@@ -170,8 +186,8 @@
                 } \
                 return value; \
             } \
-        ) \
-        return mkxp_sandbox::sb()->bind<struct coro>()()(self, value); \
+        }; \
+        return sb()->bind<struct coro>()()(self, value); \
     }
 
 #define SANDBOX_DEF_PROP_I(S, prop, name) SANDBOX_DEF_PROP(int32_t, rb_ll2inum, rb_num2int, S, prop, name)
@@ -180,10 +196,12 @@
 
 #define SANDBOX_DEF_PROP_OBJ_REF(S, V, prop, name) \
     static VALUE get_##name(VALUE self) { \
-        return mkxp_sandbox::sb()->bind<struct rb_iv_get>()()(self, #name); \
+        using namespace ::mkxp_sandbox; \
+        return sb()->bind<struct rb_iv_get>()()(self, #name); \
     } \
     static VALUE set_##name(VALUE self, VALUE value) { \
-        SANDBOX_COROUTINE(coro, \
+        using namespace ::mkxp_sandbox; \
+        struct coro : boost::asio::coroutine { \
             VALUE operator()(VALUE self, VALUE value) { \
                 BOOST_ASIO_CORO_REENTER (this) { \
                     { \
@@ -195,15 +213,17 @@
                 } \
                 return value; \
             } \
-        ) \
-        return mkxp_sandbox::sb()->bind<struct coro>()()(self, value); \
+        }; \
+        return sb()->bind<struct coro>()()(self, value); \
     }
 
 #define SANDBOX_DEF_PROP_OBJ_VAL(S, V, prop, name) \
     static VALUE get_##name(VALUE self) { \
-        return mkxp_sandbox::sb()->bind<struct rb_iv_get>()()(self, #name); \
+        using namespace ::mkxp_sandbox; \
+        return sb()->bind<struct rb_iv_get>()()(self, #name); \
     } \
     static VALUE set_##name(VALUE self, VALUE value) { \
+        using namespace ::mkxp_sandbox; \
         S *s = get_private_data<S>(self); \
         V *v = get_private_data<V>(value); \
         s->set##prop(*v); \
@@ -212,10 +232,12 @@
 
 #define SANDBOX_DEF_GFX_PROP_B(S, prop, name) \
     static VALUE get_##name(VALUE self) { \
+        using namespace ::mkxp_sandbox; \
         S *s = get_private_data<S>(self); \
         return SANDBOX_BOOL_TO_VALUE(s->get##prop()); \
     } \
     static VALUE set_##name(VALUE self, VALUE value) { \
+        using namespace ::mkxp_sandbox; \
         S *s = get_private_data<S>(self); \
         bool v = SANDBOX_VALUE_TO_BOOL(value); \
         GFX_GUARD_EXC(s->set##prop(v);); \
@@ -224,10 +246,12 @@
 
 #define SANDBOX_DEF_GFX_PROP(V, num2val, val2num, S, prop, name) \
     static VALUE get_##name(VALUE self) { \
-        return mkxp_sandbox::sb()->bind<struct num2val>()()(get_private_data<S>(self)->get##prop()); \
+        using namespace ::mkxp_sandbox; \
+        return sb()->bind<struct num2val>()()(get_private_data<S>(self)->get##prop()); \
     } \
     static VALUE set_##name(VALUE self, VALUE value) { \
-        SANDBOX_COROUTINE(coro, \
+        using namespace ::mkxp_sandbox; \
+        struct coro : boost::asio::coroutine { \
             VALUE operator()(VALUE self, VALUE value) { \
                 V v; \
                 BOOST_ASIO_CORO_REENTER (this) { \
@@ -237,8 +261,8 @@
                 } \
                 return value; \
             } \
-        ) \
-        return mkxp_sandbox::sb()->bind<struct coro>()()(self, value); \
+        }; \
+        return sb()->bind<struct coro>()()(self, value); \
     }
 
 #define SANDBOX_DEF_GFX_PROP_I(S, prop, name) SANDBOX_DEF_GFX_PROP(int32_t, rb_ll2inum, rb_num2int, S, prop, name)
@@ -247,10 +271,12 @@
 
 #define SANDBOX_DEF_GFX_PROP_OBJ_REF(S, V, prop, name) \
     static VALUE get_##name(VALUE self) { \
-        return mkxp_sandbox::sb()->bind<struct rb_iv_get>()()(self, #name); \
+        using namespace ::mkxp_sandbox; \
+        return sb()->bind<struct rb_iv_get>()()(self, #name); \
     } \
     static VALUE set_##name(VALUE self, VALUE value) { \
-        SANDBOX_COROUTINE(coro, \
+        using namespace ::mkxp_sandbox; \
+        struct coro : boost::asio::coroutine { \
             VALUE operator()(VALUE self, VALUE value) { \
                 BOOST_ASIO_CORO_REENTER (this) { \
                     { \
@@ -262,15 +288,17 @@
                 } \
                 return value; \
             } \
-        ) \
-        return mkxp_sandbox::sb()->bind<struct coro>()()(self, value); \
+        }; \
+        return sb()->bind<struct coro>()()(self, value); \
     }
 
 #define SANDBOX_DEF_GFX_PROP_OBJ_VAL(S, V, prop, name) \
     static VALUE get_##name(VALUE self) { \
-        return mkxp_sandbox::sb()->bind<struct rb_iv_get>()()(self, #name); \
+        using namespace ::mkxp_sandbox; \
+        return sb()->bind<struct rb_iv_get>()()(self, #name); \
     } \
     static VALUE set_##name(VALUE self, VALUE value) { \
+        using namespace ::mkxp_sandbox; \
         S *s = get_private_data<S>(self); \
         V *v = get_private_data<V>(value); \
         GFX_GUARD_EXC(s->set##prop(*v);); \
@@ -279,9 +307,11 @@
 
 #define SANDBOX_DEF_GRA_PROP_B(prop, name) \
     static VALUE get_##name(VALUE self) { \
+        using namespace ::mkxp_sandbox; \
         return SANDBOX_BOOL_TO_VALUE(shState->graphics().get##prop()); \
     } \
     static VALUE set_##name(VALUE self, VALUE value) { \
+        using namespace ::mkxp_sandbox; \
         bool v = SANDBOX_VALUE_TO_BOOL(value); \
         GFX_LOCK; \
         shState->graphics().set##prop(v); \
@@ -291,10 +321,12 @@
 
 #define SANDBOX_DEF_GRA_PROP(V, num2val, val2num, prop, name) \
     static VALUE get_##name(VALUE self) { \
-        return mkxp_sandbox::sb()->bind<struct num2val>()()(shState->graphics().get##prop()); \
+        using namespace ::mkxp_sandbox; \
+        return sb()->bind<struct num2val>()()(shState->graphics().get##prop()); \
     } \
     static VALUE set_##name(VALUE self, VALUE value) { \
-        SANDBOX_COROUTINE(coro, \
+        using namespace ::mkxp_sandbox; \
+        struct coro : boost::asio::coroutine { \
             VALUE operator()(VALUE self, VALUE value) { \
                 V v; \
                 BOOST_ASIO_CORO_REENTER (this) { \
@@ -305,8 +337,8 @@
                 } \
                 return value; \
             } \
-        ) \
-        return mkxp_sandbox::sb()->bind<struct coro>()()(self, value); \
+        }; \
+        return sb()->bind<struct coro>()()(self, value); \
     }
 
 #define SANDBOX_DEF_GRA_PROP_I(prop, name) SANDBOX_DEF_GRA_PROP(int32_t, rb_ll2inum, rb_num2int, prop, name)
@@ -315,10 +347,12 @@
 
 #define SANDBOX_DEF_GRA_PROP_OBJ_REF(V, prop, name) \
     static VALUE get_##name(VALUE self) { \
-        return mkxp_sandbox::sb()->bind<struct rb_iv_get>()()(self, #name); \
+        using namespace ::mkxp_sandbox; \
+        return sb()->bind<struct rb_iv_get>()()(self, #name); \
     } \
     static VALUE set_##name(VALUE self, VALUE value) { \
-        SANDBOX_COROUTINE(coro, \
+        using namespace ::mkxp_sandbox; \
+        struct coro : boost::asio::coroutine { \
             VALUE operator()(VALUE self, VALUE value) { \
                 BOOST_ASIO_CORO_REENTER (this) { \
                     { \
@@ -331,15 +365,17 @@
                 } \
                 return value; \
             } \
-        ) \
-        return mkxp_sandbox::sb()->bind<struct coro>()()(self, value); \
+        }; \
+        return sb()->bind<struct coro>()()(self, value); \
     }
 
 #define SANDBOX_DEF_GRA_PROP_OBJ_VAL(V, prop, name) \
     static VALUE get_##name(VALUE self) { \
-        return mkxp_sandbox::sb()->bind<struct rb_iv_get>()()(self, #name); \
+        using namespace ::mkxp_sandbox; \
+        return sb()->bind<struct rb_iv_get>()()(self, #name); \
     } \
     static VALUE set_##name(VALUE self, VALUE value) { \
+        using namespace ::mkxp_sandbox; \
         V *v = get_private_data<V>(value); \
         GFX_LOCK; \
         shState->graphics().set##prop(*v); \
@@ -366,7 +402,7 @@ namespace mkxp_sandbox {
     }
 
     // Gets the length of a Ruby object.
-    SANDBOX_COROUTINE(get_length,
+    struct get_length : boost::asio::coroutine {
         ID id;
         VALUE length_value;
         wasm_size_t result;
@@ -380,10 +416,10 @@ namespace mkxp_sandbox {
 
             return result;
         }
-    )
+    };
 
     // Gets the bytesize of a Ruby object.
-    SANDBOX_COROUTINE(get_bytesize,
+    struct get_bytesize : boost::asio::coroutine {
         ID id;
         VALUE length_value;
         wasm_size_t result;
@@ -397,9 +433,9 @@ namespace mkxp_sandbox {
 
             return result;
         }
-    )
+    };
 
-    SANDBOX_COROUTINE(wrap_property,
+    struct wrap_property : boost::asio::coroutine {
         VALUE obj;
 
         VALUE operator()(VALUE self, void *ptr, const char *iv, VALUE klass) {
@@ -411,10 +447,10 @@ namespace mkxp_sandbox {
 
             return obj;
         }
-    )
+    };
 
     // Prints the backtrace of a Ruby exception to the log.
-    SANDBOX_COROUTINE(log_backtrace,
+    struct log_backtrace : boost::asio::coroutine {
         ID id;
         VALUE backtrace;
         VALUE separator;
@@ -432,7 +468,7 @@ namespace mkxp_sandbox {
                 mkxp_retro::log_printf(RETRO_LOG_ERROR, "%s\n", **sb() + backtrace_str);
             }
         }
-    )
+    };
 }
 
 #endif // MKXPZ_SANDBOX_BINDING_UTIL_H
diff --git a/binding-sandbox/bitmap-binding.h b/binding-sandbox/bitmap-binding.h
index c13d6f77..0a74aec0 100644
--- a/binding-sandbox/bitmap-binding.h
+++ b/binding-sandbox/bitmap-binding.h
@@ -32,7 +32,7 @@ namespace mkxp_sandbox {
     static struct mkxp_sandbox::bindings::rb_data_type bitmap_type;
     static VALUE bitmap_class;
 
-    SANDBOX_COROUTINE(bitmap_init_props,
+    struct bitmap_init_props : boost::asio::coroutine {
         VALUE font;
         VALUE hires;
         VALUE hires_font;
@@ -55,14 +55,14 @@ namespace mkxp_sandbox {
                 bitmap->setInitFont(get_private_data<Font>(font));
             }
         }
-    )
+    };
 
-    SANDBOX_COROUTINE(bitmap_binding_init,
+    struct bitmap_binding_init : boost::asio::coroutine {
         SANDBOX_DEF_ALLOC(bitmap_type)
         SANDBOX_DEF_DFREE(Bitmap)
 
         static VALUE initialize(int32_t argc, wasm_ptr_t argv, VALUE self) {
-            SANDBOX_COROUTINE(coro,
+            struct coro : boost::asio::coroutine {
                 Bitmap *bitmap;
                 wasm_ptr_t filename;
                 wasm_size_t width;
@@ -85,13 +85,13 @@ namespace mkxp_sandbox {
 
                     return SANDBOX_NIL;
                 }
-            )
+            };
 
             return sb()->bind<struct coro>()()(argc, argv, self);
         }
 
         static VALUE initialize_copy(VALUE self, VALUE value) {
-            SANDBOX_COROUTINE(coro,
+            struct coro : boost::asio::coroutine {
                 Bitmap *bitmap;
                 Bitmap *orig;
 
@@ -113,7 +113,7 @@ namespace mkxp_sandbox {
 
                     return self;
                 }
-            )
+            };
 
             return sb()->bind<struct coro>()()(self, value);
         }
@@ -142,7 +142,7 @@ namespace mkxp_sandbox {
         SANDBOX_DEF_GFX_PROP_OBJ_REF(Bitmap, Bitmap, Hires, hires);
 
         static VALUE rect(VALUE self) {
-            SANDBOX_COROUTINE(coro,
+            struct coro : boost::asio::coroutine {
                 VALUE obj;
 
                 VALUE operator()(VALUE self) {
@@ -153,13 +153,13 @@ namespace mkxp_sandbox {
 
                     return obj;
                 }
-            )
+            };
 
             return sb()->bind<struct coro>()()(self);
         }
 
         static VALUE blt(int32_t argc, wasm_ptr_t argv, VALUE self) {
-            SANDBOX_COROUTINE(coro,
+            struct coro : boost::asio::coroutine {
                 int x;
                 int y;
                 VALUE srcObj;
@@ -189,13 +189,13 @@ namespace mkxp_sandbox {
 
                     return self;
                 }
-            )
+            };
 
             return sb()->bind<struct coro>()()(argc, argv, self);
         }
 
         static VALUE stretch_blt(int32_t argc, wasm_ptr_t argv, VALUE self) {
-            SANDBOX_COROUTINE(coro,
+            struct coro : boost::asio::coroutine {
                 VALUE destRectObj;
                 VALUE srcObj;
                 VALUE srcRectObj;
@@ -224,13 +224,13 @@ namespace mkxp_sandbox {
 
                     return self;
                 }
-            )
+            };
 
             return sb()->bind<struct coro>()()(argc, argv, self);
         }
 
         static VALUE fill_rect(int32_t argc, wasm_ptr_t argv, VALUE self) {
-            SANDBOX_COROUTINE(coro,
+            struct coro : boost::asio::coroutine {
                 Bitmap *bitmap;
                 int x;
                 int y;
@@ -254,7 +254,7 @@ namespace mkxp_sandbox {
 
                     return SANDBOX_NIL;
                 }
-            )
+            };
 
             return sb()->bind<struct coro>()()(argc, argv, self);
         }
@@ -265,7 +265,7 @@ namespace mkxp_sandbox {
         }
 
         static VALUE get_pixel(VALUE self, VALUE xval, VALUE yval) {
-            SANDBOX_COROUTINE(coro,
+            struct coro : boost::asio::coroutine {
                 Bitmap *bitmap;
                 int x;
                 int y;
@@ -295,13 +295,13 @@ namespace mkxp_sandbox {
 
                     return obj;
                 }
-            )
+            };
 
             return sb()->bind<struct coro>()()(self, xval, yval);
         }
 
         static VALUE set_pixel(VALUE self, VALUE xval, VALUE yval, VALUE colorObj) {
-            SANDBOX_COROUTINE(coro,
+            struct coro : boost::asio::coroutine {
                 Bitmap *bitmap;
                 int x;
                 int y;
@@ -319,13 +319,13 @@ namespace mkxp_sandbox {
 
                     return self;
                 }
-            )
+            };
 
             return sb()->bind<struct coro>()()(self, xval, yval, colorObj);
         }
 
         static VALUE hue_change(VALUE self, VALUE hueval) {
-            SANDBOX_COROUTINE(coro,
+            struct coro : boost::asio::coroutine {
                 Bitmap *bitmap;
                 int hue;
 
@@ -340,13 +340,13 @@ namespace mkxp_sandbox {
 
                     return self;
                 }
-            )
+            };
 
             return sb()->bind<struct coro>()()(self, hueval);
         }
 
         static VALUE draw_text(int32_t argc, wasm_ptr_t argv, VALUE self) {
-            SANDBOX_COROUTINE(coro,
+            struct coro : boost::asio::coroutine {
                 Bitmap *bitmap;
                 wasm_ptr_t str;
                 VALUE obj;
@@ -395,13 +395,13 @@ namespace mkxp_sandbox {
 
                     return SANDBOX_NIL;
                 }
-            )
+            };
 
             return sb()->bind<struct coro>()()(argc, argv, self);
         }
 
         static VALUE text_size(VALUE self, VALUE text) {
-            SANDBOX_COROUTINE(coro,
+            struct coro : boost::asio::coroutine {
                 wasm_ptr_t str;
                 VALUE obj;
 
@@ -419,13 +419,13 @@ namespace mkxp_sandbox {
 
                     return obj;
                 }
-            )
+            };
 
             return sb()->bind<struct coro>()()(self, text);
         }
 
         static VALUE get_raw_data(VALUE self) {
-            SANDBOX_COROUTINE(coro,
+            struct coro : boost::asio::coroutine {
                 VALUE value;
                 wasm_ptr_t str;
 
@@ -442,13 +442,13 @@ namespace mkxp_sandbox {
 
                     return value;
                 }
-            )
+            };
 
             return sb()->bind<struct coro>()()(self);
         }
 
         static VALUE set_raw_data(VALUE self, VALUE value) {
-            SANDBOX_COROUTINE(coro,
+            struct coro : boost::asio::coroutine {
                 wasm_ptr_t str;
                 wasm_size_t size;
 
@@ -462,13 +462,13 @@ namespace mkxp_sandbox {
 
                     return self;
                 }
-            )
+            };
 
             return sb()->bind<struct coro>()()(self, value);
         }
 
         static VALUE to_file(VALUE self, VALUE value) {
-            SANDBOX_COROUTINE(coro,
+            struct coro : boost::asio::coroutine {
                 wasm_ptr_t str;
 
                 VALUE operator()(VALUE self, VALUE value) {
@@ -480,13 +480,13 @@ namespace mkxp_sandbox {
 
                     return SANDBOX_NIL;
                 }
-            )
+            };
 
             return sb()->bind<struct coro>()()(self, value);
         }
 
         static VALUE snap_to_bitmap(int32_t argc, wasm_ptr_t argv, VALUE self) {
-            SANDBOX_COROUTINE(coro,
+            struct coro : boost::asio::coroutine {
                 Bitmap *bitmap;
                 VALUE obj;
                 int32_t pos;
@@ -509,13 +509,13 @@ namespace mkxp_sandbox {
 
                     return obj;
                 }
-            )
+            };
 
             return sb()->bind<struct coro>()()(argc, argv, self);
         }
 
         static VALUE gradient_fill_rect(int32_t argc, wasm_ptr_t argv, VALUE self) {
-            SANDBOX_COROUTINE(coro,
+            struct coro : boost::asio::coroutine {
                 int32_t x;
                 int32_t y;
                 int32_t w;
@@ -547,13 +547,13 @@ namespace mkxp_sandbox {
 
                     return SANDBOX_NIL;
                 }
-            )
+            };
 
             return sb()->bind<struct coro>()()(argc, argv, self);
         }
 
         static VALUE clear_rect(int32_t argc, wasm_ptr_t argv, VALUE self) {
-            SANDBOX_COROUTINE(coro,
+            struct coro : boost::asio::coroutine {
                 int32_t x;
                 int32_t y;
                 int32_t w;
@@ -574,7 +574,7 @@ namespace mkxp_sandbox {
 
                     return SANDBOX_NIL;
                 }
-            )
+            };
 
             return sb()->bind<struct coro>()()(argc, argv, self);
         }
@@ -585,7 +585,7 @@ namespace mkxp_sandbox {
         }
 
         static VALUE radial_blur(VALUE self, VALUE angle, VALUE divisions) {
-            SANDBOX_COROUTINE(coro,
+            struct coro : boost::asio::coroutine {
                 int32_t a;
                 int32_t d;
 
@@ -598,7 +598,7 @@ namespace mkxp_sandbox {
 
                     return SANDBOX_NIL;
                 }
-            )
+            };
 
             return sb()->bind<struct coro>()()(self, angle, divisions);
         }
@@ -636,7 +636,7 @@ namespace mkxp_sandbox {
         }
 
         static VALUE goto_and_play(VALUE self, VALUE value) {
-            SANDBOX_COROUTINE(coro,
+            struct coro : boost::asio::coroutine {
                 int32_t frame;
 
                 VALUE operator()(VALUE self, VALUE value) {
@@ -648,13 +648,13 @@ namespace mkxp_sandbox {
 
                     return SANDBOX_NIL;
                 }
-            )
+            };
 
             return sb()->bind<struct coro>()()(self, value);
         }
 
         static VALUE goto_and_stop(VALUE self, VALUE value) {
-            SANDBOX_COROUTINE(coro,
+            struct coro : boost::asio::coroutine {
                 int32_t frame;
 
                 VALUE operator()(VALUE self, VALUE value) {
@@ -666,7 +666,7 @@ namespace mkxp_sandbox {
 
                     return SANDBOX_NIL;
                 }
-            )
+            };
 
             return sb()->bind<struct coro>()()(self, value);
         }
@@ -680,7 +680,7 @@ namespace mkxp_sandbox {
         }
 
         static VALUE add_frame(int32_t argc, wasm_ptr_t argv, VALUE self) {
-            SANDBOX_COROUTINE(coro,
+            struct coro : boost::asio::coroutine {
                 VALUE value;
                 int32_t pos;
 
@@ -705,13 +705,13 @@ namespace mkxp_sandbox {
 
                     return value;
                 }
-            )
+            };
 
             return sb()->bind<struct coro>()()(argc, argv, self);
         }
 
         static VALUE remove_frame(int32_t argc, wasm_ptr_t argv, VALUE self) {
-            SANDBOX_COROUTINE(coro,
+            struct coro : boost::asio::coroutine {
                 int32_t pos;
 
                 VALUE operator()(int32_t argc, wasm_ptr_t argv, VALUE self) {
@@ -730,7 +730,7 @@ namespace mkxp_sandbox {
 
                     return SANDBOX_NIL;
                 }
-            )
+            };
 
             return sb()->bind<struct coro>()()(argc, argv, self);
         }
@@ -755,7 +755,7 @@ namespace mkxp_sandbox {
         }
 
         static VALUE set_font(VALUE self, VALUE value) {
-            SANDBOX_COROUTINE(coro,
+            struct coro : boost::asio::coroutine {
                 VALUE f;
                 VALUE prop;
 
@@ -790,7 +790,7 @@ namespace mkxp_sandbox {
 
                     return value;
                 }
-            )
+            };
 
             return sb()->bind<struct coro>()()(self, value);
         }
@@ -851,7 +851,7 @@ namespace mkxp_sandbox {
                 SANDBOX_INIT_PROP_BIND(bitmap_class, font);
             }
         }
-    )
+    };
 }
 
 #endif // MKXPZ_SANDBOX_BITMAP_BINDING_H
diff --git a/binding-sandbox/etc-binding.h b/binding-sandbox/etc-binding.h
index 7b135522..1e504fcc 100644
--- a/binding-sandbox/etc-binding.h
+++ b/binding-sandbox/etc-binding.h
@@ -36,14 +36,14 @@ namespace mkxp_sandbox {
     static struct mkxp_sandbox::bindings::rb_data_type rect_type;
     static VALUE rect_class;
 
-    SANDBOX_COROUTINE(etc_binding_init,
-        SANDBOX_COROUTINE(color_binding_init,
+    struct etc_binding_init : boost::asio::coroutine {
+        struct color_binding_init : boost::asio::coroutine {
             SANDBOX_DEF_ALLOC_WITH_INIT(color_type, new Color)
             SANDBOX_DEF_DFREE(Color)
             SANDBOX_DEF_LOAD(Color)
 
             static VALUE initialize(int32_t argc, wasm_ptr_t argv, VALUE self) {
-                SANDBOX_COROUTINE(coro,
+                struct coro : boost::asio::coroutine {
                     Color *color;
                     double red;
                     double green;
@@ -71,13 +71,13 @@ namespace mkxp_sandbox {
 
                         return SANDBOX_NIL;
                     }
-                )
+                };
 
                 return sb()->bind<struct coro>()()(argc, argv, self);
             }
 
             static VALUE initialize_copy(VALUE self, VALUE value) {
-                SANDBOX_COROUTINE(coro,
+                struct coro : boost::asio::coroutine {
                     VALUE operator()(VALUE self, VALUE value) {
                         BOOST_ASIO_CORO_REENTER (this) {
                             if (self != value) {
@@ -88,13 +88,13 @@ namespace mkxp_sandbox {
 
                         return self;
                     }
-                )
+                };
 
                 return sb()->bind<struct coro>()()(self, value);
             }
 
             static VALUE set(int32_t argc, wasm_ptr_t argv, VALUE self) {
-                SANDBOX_COROUTINE(coro,
+                struct coro : boost::asio::coroutine {
                     double red;
                     double green;
                     double blue;
@@ -119,7 +119,7 @@ namespace mkxp_sandbox {
 
                         return SANDBOX_NIL;
                     }
-                )
+                };
 
                 return sb()->bind<struct coro>()()(argc, argv, self);
             }
@@ -130,7 +130,7 @@ namespace mkxp_sandbox {
             SANDBOX_DEF_PROP_D(Color, Alpha, alpha);
 
             static VALUE equal(VALUE self, VALUE other) {
-                SANDBOX_COROUTINE(coro,
+                struct coro : boost::asio::coroutine {
                     VALUE value;
 
                     VALUE operator()(VALUE self, VALUE other) {
@@ -146,7 +146,7 @@ namespace mkxp_sandbox {
 
                         return value;
                     }
-                )
+                };
 
                 return sb()->bind<struct coro>()()(self, other);
             }
@@ -177,15 +177,15 @@ namespace mkxp_sandbox {
                     SANDBOX_AWAIT(rb_define_method, color_class, "inspect", (VALUE (*)(ANYARGS))stringify, 0);
                 }
             }
-        )
+        };
 
-        SANDBOX_COROUTINE(tone_binding_init,
+        struct tone_binding_init : boost::asio::coroutine {
             SANDBOX_DEF_ALLOC_WITH_INIT(tone_type, new Tone)
             SANDBOX_DEF_DFREE(Tone)
             SANDBOX_DEF_LOAD(Tone)
 
             static VALUE initialize(int32_t argc, wasm_ptr_t argv, VALUE self) {
-                SANDBOX_COROUTINE(coro,
+                struct coro : boost::asio::coroutine {
                     Tone *tone;
                     double red;
                     double green;
@@ -213,13 +213,13 @@ namespace mkxp_sandbox {
 
                         return SANDBOX_NIL;
                     }
-                )
+                };
 
                 return sb()->bind<struct coro>()()(argc, argv, self);
             }
 
             static VALUE initialize_copy(VALUE self, VALUE value) {
-                SANDBOX_COROUTINE(coro,
+                struct coro : boost::asio::coroutine {
                     VALUE operator()(VALUE self, VALUE value) {
                         BOOST_ASIO_CORO_REENTER (this) {
                             if (self != value) {
@@ -230,13 +230,13 @@ namespace mkxp_sandbox {
 
                         return self;
                     }
-                )
+                };
 
                 return sb()->bind<struct coro>()()(self, value);
             }
 
             static VALUE set(int32_t argc, wasm_ptr_t argv, VALUE self) {
-                SANDBOX_COROUTINE(coro,
+                struct coro : boost::asio::coroutine {
                     double red;
                     double green;
                     double blue;
@@ -261,7 +261,7 @@ namespace mkxp_sandbox {
 
                         return SANDBOX_NIL;
                     }
-                )
+                };
 
                 return sb()->bind<struct coro>()()(argc, argv, self);
             }
@@ -272,7 +272,7 @@ namespace mkxp_sandbox {
             SANDBOX_DEF_PROP_D(Tone, Gray, gray);
 
             static VALUE equal(VALUE self, VALUE other) {
-                SANDBOX_COROUTINE(coro,
+                struct coro : boost::asio::coroutine {
                     VALUE value;
 
                     VALUE operator()(VALUE self, VALUE other) {
@@ -288,7 +288,7 @@ namespace mkxp_sandbox {
 
                         return value;
                     }
-                )
+                };
 
                 return sb()->bind<struct coro>()()(self, other);
             }
@@ -319,15 +319,15 @@ namespace mkxp_sandbox {
                     SANDBOX_AWAIT(rb_define_method, tone_class, "inspect", (VALUE (*)(ANYARGS))stringify, 0);
                 }
             }
-        )
+        };
 
-        SANDBOX_COROUTINE(rect_binding_init,
+        struct rect_binding_init : boost::asio::coroutine {
             SANDBOX_DEF_ALLOC_WITH_INIT(rect_type, new Rect)
             SANDBOX_DEF_DFREE(Rect)
             SANDBOX_DEF_LOAD(Rect)
 
             static VALUE initialize(int32_t argc, wasm_ptr_t argv, VALUE self) {
-                SANDBOX_COROUTINE(coro,
+                struct coro : boost::asio::coroutine {
                     Rect *rect;
                     int x;
                     int y;
@@ -351,13 +351,13 @@ namespace mkxp_sandbox {
 
                         return SANDBOX_NIL;
                     }
-                )
+                };
 
                 return sb()->bind<struct coro>()()(argc, argv, self);
             }
 
             static VALUE initialize_copy(VALUE self, VALUE value) {
-                SANDBOX_COROUTINE(coro,
+                struct coro : boost::asio::coroutine {
                     VALUE operator()(VALUE self, VALUE value) {
                         BOOST_ASIO_CORO_REENTER (this) {
                             if (self != value) {
@@ -368,13 +368,13 @@ namespace mkxp_sandbox {
 
                         return self;
                     }
-                )
+                };
 
                 return sb()->bind<struct coro>()()(self, value);
             }
 
             static VALUE set(int32_t argc, wasm_ptr_t argv, VALUE self) {
-                SANDBOX_COROUTINE(coro,
+                struct coro : boost::asio::coroutine {
                     int x;
                     int y;
                     int width;
@@ -395,7 +395,7 @@ namespace mkxp_sandbox {
 
                         return SANDBOX_NIL;
                     }
-                )
+                };
 
                 return sb()->bind<struct coro>()()(argc, argv, self);
             }
@@ -411,7 +411,7 @@ namespace mkxp_sandbox {
             SANDBOX_DEF_PROP_D(Rect, Height, height);
 
             static VALUE equal(VALUE self, VALUE other) {
-                SANDBOX_COROUTINE(coro,
+                struct coro : boost::asio::coroutine {
                     VALUE value;
 
                     VALUE operator()(VALUE self, VALUE other) {
@@ -427,7 +427,7 @@ namespace mkxp_sandbox {
 
                         return value;
                     }
-                )
+                };
 
                 return sb()->bind<struct coro>()()(self, other);
             }
@@ -459,7 +459,7 @@ namespace mkxp_sandbox {
                     SANDBOX_AWAIT(rb_define_method, rect_class, "inspect", (VALUE (*)(ANYARGS))stringify, 0);
                 }
             }
-        )
+        };
 
         void operator()() {
             BOOST_ASIO_CORO_REENTER (this) {
@@ -468,7 +468,7 @@ namespace mkxp_sandbox {
                 SANDBOX_AWAIT(rect_binding_init);
             }
         }
-    )
+    };
 }
 
 #endif // MKXPZ_SANDBOX_ETC_BINDING_H
diff --git a/binding-sandbox/font-binding.h b/binding-sandbox/font-binding.h
index 084b936e..d05a7b39 100644
--- a/binding-sandbox/font-binding.h
+++ b/binding-sandbox/font-binding.h
@@ -33,7 +33,7 @@ namespace mkxp_sandbox {
     static struct mkxp_sandbox::bindings::rb_data_type font_type;
     static VALUE font_class;
 
-    SANDBOX_COROUTINE(font_binding_init,
+    struct font_binding_init : boost::asio::coroutine {
         SANDBOX_DEF_ALLOC(font_type)
         SANDBOX_DEF_DFREE(Font)
 
@@ -41,7 +41,7 @@ namespace mkxp_sandbox {
         VALUE default_name;
         wasm_size_t default_name_index;
 
-        SANDBOX_COROUTINE(collect_strings,
+        struct collect_strings : boost::asio::coroutine {
             VALUE value;
             VALUE entry;
             wasm_ptr_t str;
@@ -72,10 +72,10 @@ namespace mkxp_sandbox {
                     }
                 }
             }
-        )
+        };
 
         static VALUE initialize(int32_t argc, wasm_ptr_t argv, VALUE self) {
-            SANDBOX_COROUTINE(coro,
+            struct coro : boost::asio::coroutine {
                 Font *font;
                 std::vector<std::string> *names;
                 VALUE names_obj;
@@ -120,13 +120,13 @@ namespace mkxp_sandbox {
                 ~coro() {
                     delete names;
                 }
-            )
+            };
 
             return sb()->bind<struct coro>()()(argc, argv, self);
         }
 
         static VALUE initialize_copy(VALUE self, VALUE value) {
-            SANDBOX_COROUTINE(coro,
+            struct coro : boost::asio::coroutine {
                 Font *font;
 
                 VALUE operator()(VALUE self, VALUE value) {
@@ -150,7 +150,7 @@ namespace mkxp_sandbox {
 
                     return self;
                 }
-            )
+            };
 
             return sb()->bind<struct coro>()()(self, value);
         }
@@ -160,7 +160,7 @@ namespace mkxp_sandbox {
         }
 
         static VALUE set_name(VALUE self, VALUE value) {
-            SANDBOX_COROUTINE(coro,
+            struct coro : boost::asio::coroutine {
                 std::vector<std::string> *names;
 
                 VALUE operator()(VALUE self, VALUE value) {
@@ -177,7 +177,7 @@ namespace mkxp_sandbox {
                 ~coro() {
                     delete names;
                 }
-            )
+            };
 
             return sb()->bind<struct coro>()()(self, value);
         }
@@ -195,7 +195,7 @@ namespace mkxp_sandbox {
         }
 
         static VALUE set_default_name(VALUE self, VALUE value) {
-            SANDBOX_COROUTINE(coro,
+            struct coro : boost::asio::coroutine {
                 std::vector<std::string> *names;
 
                 VALUE operator()(VALUE self, VALUE value) {
@@ -212,7 +212,7 @@ namespace mkxp_sandbox {
                 ~coro() {
                     delete names;
                 }
-            )
+            };
 
             return sb()->bind<struct coro>()()(self, value);
         }
@@ -226,7 +226,7 @@ namespace mkxp_sandbox {
         SANDBOX_DEF_CLASS_PROP_OBJ_VAL(Font, Color, DefaultOutColor, default_out_color);
 
         static VALUE exist(VALUE self, VALUE value) {
-            SANDBOX_COROUTINE(coro,
+            struct coro : boost::asio::coroutine {
                 wasm_ptr_t str;
                 VALUE is_string;
 
@@ -243,7 +243,7 @@ namespace mkxp_sandbox {
 
                     return SANDBOX_UNDEF;
                 }
-            )
+            };
 
             return sb()->bind<struct coro>()()(self, value);
         }
@@ -309,7 +309,7 @@ namespace mkxp_sandbox {
                 SANDBOX_AWAIT(rb_define_singleton_method, font_class, "exist?", (VALUE (*)(ANYARGS))exist, 1);
             }
         }
-    )
+    };
 }
 
 #endif // MKXPZ_SANDBOX_FONT_BINDING_H
diff --git a/binding-sandbox/graphics-binding.h b/binding-sandbox/graphics-binding.h
index 060f3bff..20c50bf3 100644
--- a/binding-sandbox/graphics-binding.h
+++ b/binding-sandbox/graphics-binding.h
@@ -32,9 +32,9 @@
 namespace mkxp_sandbox {
     static VALUE graphics_module;
 
-    SANDBOX_COROUTINE(graphics_binding_init,
+    struct graphics_binding_init : boost::asio::coroutine {
         static VALUE delta(VALUE self) {
-            SANDBOX_COROUTINE(coro,
+            struct coro : boost::asio::coroutine {
                 VALUE value;
 
                 VALUE operator()(VALUE self) {
@@ -46,13 +46,13 @@ namespace mkxp_sandbox {
 
                     return value;
                 }
-            )
+            };
 
             return sb()->bind<struct coro>()()(self);
         }
 
         static VALUE update(VALUE self) {
-            SANDBOX_COROUTINE(coro,
+            struct coro : boost::asio::coroutine {
                 VALUE operator()(VALUE self) {
                     BOOST_ASIO_CORO_REENTER (this) {
                         if (shState->graphics().update()) {
@@ -62,7 +62,7 @@ namespace mkxp_sandbox {
 
                     return SANDBOX_NIL;
                 }
-            )
+            };
 
             return sb()->bind<struct coro>()()(self);
         }
@@ -73,7 +73,7 @@ namespace mkxp_sandbox {
         }
 
         static VALUE transition(int32_t argc, wasm_ptr_t argv, VALUE self) {
-            SANDBOX_COROUTINE(coro,
+            struct coro : boost::asio::coroutine {
                 Bitmap *trans_map;
                 wasm_ptr_t str;
                 int32_t duration;
@@ -125,7 +125,7 @@ namespace mkxp_sandbox {
                         delete trans_map;
                     }
                 }
-            )
+            };
 
             return sb()->bind<struct coro>()()(argc, argv, self);
         }
@@ -138,7 +138,7 @@ namespace mkxp_sandbox {
         }
 
         static VALUE screenshot(VALUE self, VALUE value) {
-            SANDBOX_COROUTINE(coro,
+            struct coro : boost::asio::coroutine {
                 wasm_ptr_t str;
 
                 VALUE operator()(VALUE self, VALUE value) {
@@ -149,7 +149,7 @@ namespace mkxp_sandbox {
 
                     return SANDBOX_NIL;
                 }
-            )
+            };
 
             return sb()->bind<struct coro>()()(self, value);
         }
@@ -183,7 +183,7 @@ namespace mkxp_sandbox {
         }
 
         static VALUE wait(VALUE self, VALUE value) {
-            SANDBOX_COROUTINE(coro,
+            struct coro : boost::asio::coroutine {
                 int32_t duration;
                 int32_t i;
 
@@ -199,13 +199,13 @@ namespace mkxp_sandbox {
 
                     return SANDBOX_NIL;
                 }
-            )
+            };
 
             return sb()->bind<struct coro>()()(self, value);
         }
 
         static VALUE fadeout(VALUE self, VALUE value) {
-            SANDBOX_COROUTINE(coro,
+            struct coro : boost::asio::coroutine {
                 int32_t duration;
                 int32_t i;
                 int32_t brightness;
@@ -223,13 +223,13 @@ namespace mkxp_sandbox {
 
                     return SANDBOX_NIL;
                 }
-            )
+            };
 
             return sb()->bind<struct coro>()()(self, value);
         }
 
         static VALUE fadein(VALUE self, VALUE value) {
-            SANDBOX_COROUTINE(coro,
+            struct coro : boost::asio::coroutine {
                 int32_t duration;
                 int32_t i;
                 int32_t brightness;
@@ -247,13 +247,13 @@ namespace mkxp_sandbox {
 
                     return SANDBOX_NIL;
                 }
-            )
+            };
 
             return sb()->bind<struct coro>()()(self, value);
         }
 
         static VALUE snap_to_bitmap(VALUE self) {
-            SANDBOX_COROUTINE(coro,
+            struct coro : boost::asio::coroutine {
                 Bitmap *bitmap;
                 VALUE obj;
 
@@ -267,13 +267,13 @@ namespace mkxp_sandbox {
 
                     return obj;
                 }
-            )
+            };
 
             return sb()->bind<struct coro>()()(self);
         }
 
         static VALUE resize_screen(VALUE self, VALUE width, VALUE height) {
-            SANDBOX_COROUTINE(coro,
+            struct coro : boost::asio::coroutine {
                 int32_t w;
                 int32_t h;
 
@@ -288,13 +288,13 @@ namespace mkxp_sandbox {
 
                     return SANDBOX_NIL;
                 }
-            )
+            };
 
             return sb()->bind<struct coro>()()(self, width, height);
         }
 
         static VALUE resize_window(int32_t argc, wasm_ptr_t argv, VALUE self) {
-            SANDBOX_COROUTINE(coro,
+            struct coro : boost::asio::coroutine {
                 int32_t w;
                 int32_t h;
 
@@ -314,7 +314,7 @@ namespace mkxp_sandbox {
 
                     return SANDBOX_NIL;
                 }
-            )
+            };
 
             return sb()->bind<struct coro>()()(argc, argv, self);
         }
@@ -327,7 +327,7 @@ namespace mkxp_sandbox {
         SANDBOX_DEF_GRA_PROP_I(Brightness, brightness);
 
         static VALUE play_movie(int32_t argc, wasm_ptr_t argv, VALUE self) {
-            SANDBOX_COROUTINE(coro,
+            struct coro : boost::asio::coroutine {
                 wasm_ptr_t str;
                 int32_t volume;
 
@@ -347,7 +347,7 @@ namespace mkxp_sandbox {
 
                     return SANDBOX_NIL;
                 }
-            )
+            };
 
             return sb()->bind<struct coro>()()(argc, argv, self);
         }
@@ -405,7 +405,7 @@ namespace mkxp_sandbox {
                 SANDBOX_INIT_MODULE_PROP_BIND(graphics_module, threadsafe);
             }
         }
-    )
+    };
 }
 
 #endif // MKXPZ_SANDBOX_GRAPHICS_BINDING_H
diff --git a/binding-sandbox/input-binding.h b/binding-sandbox/input-binding.h
index 38eaf078..7e8e8f25 100644
--- a/binding-sandbox/input-binding.h
+++ b/binding-sandbox/input-binding.h
@@ -62,8 +62,8 @@ namespace mkxp_sandbox {
         {"MOUSEX2", Input::MouseX2},
     };
 
-    SANDBOX_COROUTINE(input_binding_init,
-        SANDBOX_COROUTINE(get_button_arg,
+    struct input_binding_init : boost::asio::coroutine {
+        struct get_button_arg : boost::asio::coroutine {
             VALUE value;
             int32_t button;
 
@@ -88,7 +88,7 @@ namespace mkxp_sandbox {
 
                 return button;
             }
-        )
+        };
 
         static VALUE delta(VALUE self) {
             return sb()->bind<struct rb_float_new>()()(mkxp_retro::input->getDelta());
@@ -100,7 +100,7 @@ namespace mkxp_sandbox {
         }
 
         static VALUE press(VALUE self, VALUE code) {
-            SANDBOX_COROUTINE(coro,
+            struct coro : boost::asio::coroutine {
                 int32_t button;
 
                 VALUE operator()(VALUE self, VALUE code) {
@@ -111,13 +111,13 @@ namespace mkxp_sandbox {
 
                     return SANDBOX_UNDEF;
                 }
-            )
+            };
 
             return sb()->bind<struct coro>()()(self, code);
         }
 
         static VALUE trigger(VALUE self, VALUE code) {
-            SANDBOX_COROUTINE(coro,
+            struct coro : boost::asio::coroutine {
                 int32_t button;
 
                 VALUE operator()(VALUE self, VALUE code) {
@@ -128,13 +128,13 @@ namespace mkxp_sandbox {
 
                     return SANDBOX_UNDEF;
                 }
-            )
+            };
 
             return sb()->bind<struct coro>()()(self, code);
         }
 
         static VALUE repeat(VALUE self, VALUE code) {
-            SANDBOX_COROUTINE(coro,
+            struct coro : boost::asio::coroutine {
                 int32_t button;
 
                 VALUE operator()(VALUE self, VALUE code) {
@@ -145,13 +145,13 @@ namespace mkxp_sandbox {
 
                     return SANDBOX_UNDEF;
                 }
-            )
+            };
 
             return sb()->bind<struct coro>()()(self, code);
         }
 
         static VALUE release(VALUE self, VALUE code) {
-            SANDBOX_COROUTINE(coro,
+            struct coro : boost::asio::coroutine {
                 int32_t button;
 
                 VALUE operator()(VALUE self, VALUE code) {
@@ -162,13 +162,13 @@ namespace mkxp_sandbox {
 
                     return SANDBOX_UNDEF;
                 }
-            )
+            };
 
             return sb()->bind<struct coro>()()(self, code);
         }
 
         static VALUE count(VALUE self, VALUE code) {
-            SANDBOX_COROUTINE(coro,
+            struct coro : boost::asio::coroutine {
                 int32_t button;
                 int32_t count;
                 VALUE value;
@@ -182,13 +182,13 @@ namespace mkxp_sandbox {
 
                     return value;
                 }
-            )
+            };
 
             return sb()->bind<struct coro>()()(self, code);
         }
 
         static VALUE time(VALUE self, VALUE code) {
-            SANDBOX_COROUTINE(coro,
+            struct coro : boost::asio::coroutine {
                 int32_t button;
                 double time;
                 VALUE value;
@@ -202,13 +202,13 @@ namespace mkxp_sandbox {
 
                     return value;
                 }
-            )
+            };
 
             return sb()->bind<struct coro>()()(self, code);
         }
 
         static VALUE pressex(VALUE self, VALUE code) {
-            SANDBOX_COROUTINE(coro,
+            struct coro : boost::asio::coroutine {
                 int32_t button;
 
                 VALUE operator()(VALUE self, VALUE code) {
@@ -219,13 +219,13 @@ namespace mkxp_sandbox {
 
                     return SANDBOX_UNDEF;
                 }
-            )
+            };
 
             return sb()->bind<struct coro>()()(self, code);
         }
 
         static VALUE triggerex(VALUE self, VALUE code) {
-            SANDBOX_COROUTINE(coro,
+            struct coro : boost::asio::coroutine {
                 int32_t button;
 
                 VALUE operator()(VALUE self, VALUE code) {
@@ -236,13 +236,13 @@ namespace mkxp_sandbox {
 
                     return SANDBOX_UNDEF;
                 }
-            )
+            };
 
             return sb()->bind<struct coro>()()(self, code);
         }
 
         static VALUE repeatex(VALUE self, VALUE code) {
-            SANDBOX_COROUTINE(coro,
+            struct coro : boost::asio::coroutine {
                 int32_t button;
 
                 VALUE operator()(VALUE self, VALUE code) {
@@ -253,13 +253,13 @@ namespace mkxp_sandbox {
 
                     return SANDBOX_UNDEF;
                 }
-            )
+            };
 
             return sb()->bind<struct coro>()()(self, code);
         }
 
         static VALUE releaseex(VALUE self, VALUE code) {
-            SANDBOX_COROUTINE(coro,
+            struct coro : boost::asio::coroutine {
                 int32_t button;
 
                 VALUE operator()(VALUE self, VALUE code) {
@@ -270,13 +270,13 @@ namespace mkxp_sandbox {
 
                     return SANDBOX_UNDEF;
                 }
-            )
+            };
 
             return sb()->bind<struct coro>()()(self, code);
         }
 
         static VALUE repeatcount(VALUE self, VALUE code) {
-            SANDBOX_COROUTINE(coro,
+            struct coro : boost::asio::coroutine {
                 int32_t button;
                 int32_t count;
                 VALUE value;
@@ -290,13 +290,13 @@ namespace mkxp_sandbox {
 
                     return value;
                 }
-            )
+            };
 
             return sb()->bind<struct coro>()()(self, code);
         }
 
         static VALUE timeex(VALUE self, VALUE code) {
-            SANDBOX_COROUTINE(coro,
+            struct coro : boost::asio::coroutine {
                 int32_t button;
                 double time;
                 VALUE value;
@@ -310,7 +310,7 @@ namespace mkxp_sandbox {
 
                     return value;
                 }
-            )
+            };
 
             return sb()->bind<struct coro>()()(self, code);
         }
@@ -394,7 +394,7 @@ namespace mkxp_sandbox {
                 }
             }
         }
-    )
+    };
 }
 
 #endif // MKXPZ_SANDBOX_INPUT_BINDING_H
diff --git a/binding-sandbox/plane-binding.h b/binding-sandbox/plane-binding.h
index 93a1341d..9e09b614 100644
--- a/binding-sandbox/plane-binding.h
+++ b/binding-sandbox/plane-binding.h
@@ -31,12 +31,12 @@ namespace mkxp_sandbox {
     static struct mkxp_sandbox::bindings::rb_data_type plane_type;
     static VALUE plane_class;
 
-    SANDBOX_COROUTINE(plane_binding_init,
+    struct plane_binding_init : boost::asio::coroutine {
         SANDBOX_DEF_ALLOC(plane_type)
         SANDBOX_DEF_DFREE(Plane)
 
         static VALUE initialize(int32_t argc, wasm_ptr_t argv, VALUE self) {
-            SANDBOX_COROUTINE(coro,
+            struct coro : boost::asio::coroutine {
                 Plane *plane;
                 VALUE viewport_obj;
                 Viewport *viewport;
@@ -73,7 +73,7 @@ namespace mkxp_sandbox {
 
                     return SANDBOX_NIL;
                 }
-            )
+            };
 
             return sb()->bind<struct coro>()()(argc, argv, self);
         }
@@ -126,7 +126,7 @@ namespace mkxp_sandbox {
                 SANDBOX_INIT_PROP_BIND(plane_class, blend_type);
             }
         }
-    )
+    };
 }
 
 #endif // MKXPZ_SANDBOX_PLANE_BINDING_H
diff --git a/binding-sandbox/sandbox.h b/binding-sandbox/sandbox.h
index f82ba655..112f4e4b 100644
--- a/binding-sandbox/sandbox.h
+++ b/binding-sandbox/sandbox.h
@@ -27,12 +27,11 @@
 #include <mkxp-sandbox-bindgen.h>
 #include "types.h"
 
-#define SANDBOX_COROUTINE(name, definition) struct name : boost::asio::coroutine { inline name(struct mkxp_sandbox::binding_base &bind) {} definition };
-
 #define SANDBOX_AWAIT(coroutine, ...) \
     do { \
         { \
-            struct mkxp_sandbox::bindings::stack_frame_guard<struct coroutine> _frame = mkxp_sandbox::sb()->bind<struct coroutine>(); \
+            using namespace ::mkxp_sandbox; \
+            struct bindings::stack_frame_guard<struct coroutine> _frame = sb()->bind<struct coroutine>(); \
             _frame()(__VA_ARGS__); \
             if (_frame().is_complete()) break; \
         } \
@@ -42,7 +41,8 @@
 #define SANDBOX_AWAIT_AND_SET(variable, coroutine, ...) \
     do { \
         { \
-            struct mkxp_sandbox::bindings::stack_frame_guard<struct coroutine> _frame = mkxp_sandbox::sb()->bind<struct coroutine>(); \
+            using namespace ::mkxp_sandbox; \
+            struct bindings::stack_frame_guard<struct coroutine> _frame = sb()->bind<struct coroutine>(); \
             auto ret = _frame()(__VA_ARGS__); \
             if (_frame().is_complete()) { \
                 variable = ret; \
@@ -54,6 +54,7 @@
 
 #define SANDBOX_YIELD \
     do { \
+        using namespace ::mkxp_sandbox; \
         sb()._begin_yield(); \
         BOOST_ASIO_CORO_YIELD; \
         sb()._end_yield(); \
diff --git a/binding-sandbox/sprite-binding.h b/binding-sandbox/sprite-binding.h
index 63e47359..4b2f797f 100644
--- a/binding-sandbox/sprite-binding.h
+++ b/binding-sandbox/sprite-binding.h
@@ -31,12 +31,12 @@ namespace mkxp_sandbox {
     static struct mkxp_sandbox::bindings::rb_data_type sprite_type;
     static VALUE sprite_class;
 
-    SANDBOX_COROUTINE(sprite_binding_init,
+    struct sprite_binding_init : boost::asio::coroutine {
         SANDBOX_DEF_ALLOC(sprite_type)
         SANDBOX_DEF_DFREE(Sprite)
 
         static VALUE initialize(int32_t argc, wasm_ptr_t argv, VALUE self) {
-            SANDBOX_COROUTINE(coro,
+            struct coro : boost::asio::coroutine {
                 Sprite *sprite;
                 VALUE viewport_obj;
                 Viewport *viewport;
@@ -69,7 +69,7 @@ namespace mkxp_sandbox {
 
                     return SANDBOX_NIL;
                 }
-            )
+            };
 
             return sb()->bind<struct coro>()()(argc, argv, self);
         }
@@ -88,7 +88,7 @@ namespace mkxp_sandbox {
         }
 
         static VALUE flash(VALUE self, VALUE obj, VALUE value) {
-            SANDBOX_COROUTINE(coro,
+            struct coro : boost::asio::coroutine {
                 int duration;
 
                 VALUE operator()(VALUE self, VALUE obj, VALUE value) {
@@ -99,7 +99,7 @@ namespace mkxp_sandbox {
 
                     return SANDBOX_NIL;
                 }
-            )
+            };
 
             return sb()->bind<struct coro>()()(self, obj, value);
         }
@@ -173,7 +173,7 @@ namespace mkxp_sandbox {
                 SANDBOX_INIT_PROP_BIND(sprite_class, blend_type);
             }
         }
-    )
+    };
 }
 
 #endif // MKXPZ_SANDBOX_SPRITE_BINDING_H
diff --git a/binding-sandbox/table-binding.h b/binding-sandbox/table-binding.h
index 3ee9997d..fa3dc835 100644
--- a/binding-sandbox/table-binding.h
+++ b/binding-sandbox/table-binding.h
@@ -31,13 +31,13 @@ namespace mkxp_sandbox {
     static struct mkxp_sandbox::bindings::rb_data_type table_type;
     static VALUE table_class;
 
-    SANDBOX_COROUTINE(table_binding_init,
+    struct table_binding_init : boost::asio::coroutine {
         SANDBOX_DEF_ALLOC_WITH_INIT(table_type, new Table(0, 0, 0))
         SANDBOX_DEF_DFREE(Table)
         SANDBOX_DEF_LOAD(Table)
 
         static VALUE initialize(int32_t argc, wasm_ptr_t argv, VALUE self) {
-            SANDBOX_COROUTINE(coro,
+            struct coro : boost::asio::coroutine {
                 int32_t x;
                 int32_t y;
                 int32_t z;
@@ -69,13 +69,13 @@ namespace mkxp_sandbox {
 
                     return SANDBOX_NIL;
                 }
-            )
+            };
 
             return sb()->bind<struct coro>()()(argc, argv, self);
         }
 
         static VALUE initialize_copy(VALUE self, VALUE value) {
-            SANDBOX_COROUTINE(coro,
+            struct coro : boost::asio::coroutine {
                 VALUE operator()(VALUE self, VALUE value) {
                     BOOST_ASIO_CORO_REENTER (this) {
                         if (self != value) {
@@ -86,13 +86,13 @@ namespace mkxp_sandbox {
 
                     return self;
                 }
-            )
+            };
 
             return sb()->bind<struct coro>()()(self, value);
         }
 
         static VALUE resize(int32_t argc, wasm_ptr_t argv, VALUE self) {
-            SANDBOX_COROUTINE(coro,
+            struct coro : boost::asio::coroutine {
                 Table *table;
                 int32_t x;
                 int32_t y;
@@ -119,7 +119,7 @@ namespace mkxp_sandbox {
 
                     return SANDBOX_NIL;
                 }
-            )
+            };
 
             return sb()->bind<struct coro>()()(argc, argv, self);
         }
@@ -137,7 +137,7 @@ namespace mkxp_sandbox {
         }
 
         static VALUE get(int32_t argc, wasm_ptr_t argv, VALUE self) {
-            SANDBOX_COROUTINE(coro,
+            struct coro : boost::asio::coroutine {
                 Table *table;
                 VALUE value;
                 int32_t x;
@@ -167,13 +167,13 @@ namespace mkxp_sandbox {
 
                     return value;
                 }
-            )
+            };
 
             return sb()->bind<struct coro>()()(argc, argv, self);
         }
 
         static VALUE set(int32_t argc, wasm_ptr_t argv, VALUE self) {
-            SANDBOX_COROUTINE(coro,
+            struct coro : boost::asio::coroutine {
                 Table *table;
                 int32_t x;
                 int32_t y;
@@ -203,7 +203,7 @@ namespace mkxp_sandbox {
 
                     return SANDBOX_UNDEF;
                 }
-            )
+            };
 
             return sb()->bind<struct coro>()()(argc, argv, self);
         }
@@ -224,7 +224,7 @@ namespace mkxp_sandbox {
                 SANDBOX_AWAIT(rb_define_method, table_class, "[]=", (VALUE (*)(ANYARGS))set, -1);
             }
         }
-    )
+    };
 }
 
 #endif // MKXPZ_SANDBOX_TABLE_BINDING_H
diff --git a/binding-sandbox/tilemap-binding.h b/binding-sandbox/tilemap-binding.h
index f0381159..cdc93f53 100644
--- a/binding-sandbox/tilemap-binding.h
+++ b/binding-sandbox/tilemap-binding.h
@@ -33,12 +33,12 @@ namespace mkxp_sandbox {
     static struct mkxp_sandbox::bindings::rb_data_type tilemap_autotiles_type;
     static VALUE tilemap_autotiles_class;
 
-    SANDBOX_COROUTINE(tilemap_binding_init,
-        SANDBOX_COROUTINE(tilemap_autotiles_binding_init,
+    struct tilemap_binding_init : boost::asio::coroutine {
+        struct tilemap_autotiles_binding_init : boost::asio::coroutine {
             SANDBOX_DEF_ALLOC(tilemap_autotiles_type)
 
             static VALUE get(VALUE self, VALUE i) {
-                SANDBOX_COROUTINE(coro,
+                struct coro : boost::asio::coroutine {
                     VALUE ary;
                     wasm_size_t index;
                     VALUE value;
@@ -52,13 +52,13 @@ namespace mkxp_sandbox {
 
                         return value;
                     }
-                )
+                };
 
                 return sb()->bind<struct coro>()()(self, i);
             }
 
             static VALUE set(VALUE self, VALUE i, VALUE obj) {
-                SANDBOX_COROUTINE(coro,
+                struct coro : boost::asio::coroutine {
                     Tilemap::Autotiles *autotiles;
                     Bitmap *bitmap;
                     VALUE ary;
@@ -84,7 +84,7 @@ namespace mkxp_sandbox {
 
                         return self;
                     }
-                )
+                };
 
                 return sb()->bind<struct coro>()()(self, i, obj);
             }
@@ -98,13 +98,13 @@ namespace mkxp_sandbox {
                     SANDBOX_AWAIT(rb_define_method, tilemap_autotiles_class, "[]=", (VALUE (*)(ANYARGS))set, 2);
                 }
             }
-        )
+        };
 
         SANDBOX_DEF_ALLOC(tilemap_type)
         SANDBOX_DEF_DFREE(Tilemap)
 
         static VALUE initialize(int32_t argc, wasm_ptr_t argv, VALUE self) {
-            SANDBOX_COROUTINE(coro,
+            struct coro : boost::asio::coroutine {
                 Tilemap *tilemap;
                 VALUE viewport_obj;
                 Viewport *viewport;
@@ -162,7 +162,7 @@ namespace mkxp_sandbox {
 
                     return SANDBOX_NIL;
                 }
-            )
+            };
 
             return sb()->bind<struct coro>()()(argc, argv, self);
         }
@@ -228,7 +228,7 @@ namespace mkxp_sandbox {
                 SANDBOX_INIT_PROP_BIND(tilemap_class, blend_type);
             }
         }
-    )
+    };
 }
 
 #endif // MKXPZ_SANDBOX_TILEMAP_BINDING_H
diff --git a/binding-sandbox/tilemapvx-binding.h b/binding-sandbox/tilemapvx-binding.h
index 87162c4e..eb9c19cd 100644
--- a/binding-sandbox/tilemapvx-binding.h
+++ b/binding-sandbox/tilemapvx-binding.h
@@ -32,12 +32,12 @@ namespace mkxp_sandbox {
     static struct mkxp_sandbox::bindings::rb_data_type bitmap_array_type;
     static VALUE bitmap_array_class;
 
-    SANDBOX_COROUTINE(tilemapvx_binding_init,
-        SANDBOX_COROUTINE(bitmap_array_binding_init,
+    struct tilemapvx_binding_init : boost::asio::coroutine {
+        struct bitmap_array_binding_init : boost::asio::coroutine {
             SANDBOX_DEF_ALLOC(bitmap_array_type)
 
             static VALUE get(VALUE self, VALUE i) {
-                SANDBOX_COROUTINE(coro,
+                struct coro : boost::asio::coroutine {
                     VALUE ary;
                     wasm_size_t index;
                     VALUE value;
@@ -51,13 +51,13 @@ namespace mkxp_sandbox {
 
                         return value;
                     }
-                )
+                };
 
                 return sb()->bind<struct coro>()()(self, i);
             }
 
             static VALUE set(VALUE self, VALUE i, VALUE obj) {
-                SANDBOX_COROUTINE(coro,
+                struct coro : boost::asio::coroutine {
                     TilemapVX::BitmapArray *bitmap_array;
                     Bitmap *bitmap;
                     VALUE ary;
@@ -83,7 +83,7 @@ namespace mkxp_sandbox {
 
                         return self;
                     }
-                )
+                };
 
                 return sb()->bind<struct coro>()()(self, i, obj);
             }
@@ -97,13 +97,13 @@ namespace mkxp_sandbox {
                     SANDBOX_AWAIT(rb_define_method, bitmap_array_class, "[]=", (VALUE (*)(ANYARGS))set, 2);
                 }
             }
-        )
+        };
 
         SANDBOX_DEF_ALLOC(tilemapvx_type)
         SANDBOX_DEF_DFREE(TilemapVX)
 
         static VALUE initialize(int32_t argc, wasm_ptr_t argv, VALUE self) {
-            SANDBOX_COROUTINE(coro,
+            struct coro : boost::asio::coroutine {
                 TilemapVX *tilemap;
                 VALUE viewport_obj;
                 Viewport *viewport;
@@ -156,7 +156,7 @@ namespace mkxp_sandbox {
 
                     return SANDBOX_NIL;
                 }
-            )
+            };
 
             return sb()->bind<struct coro>()()(argc, argv, self);
         }
@@ -217,7 +217,7 @@ namespace mkxp_sandbox {
                 SANDBOX_INIT_PROP_BIND(tilemapvx_class, oy);
             }
         }
-    )
+    };
 }
 
 #endif // MKXPZ_SANDBOX_TILEMAPVX_BINDING_H
diff --git a/binding-sandbox/viewport-binding.h b/binding-sandbox/viewport-binding.h
index cf0dc2b5..4bb48037 100644
--- a/binding-sandbox/viewport-binding.h
+++ b/binding-sandbox/viewport-binding.h
@@ -31,12 +31,12 @@ namespace mkxp_sandbox {
     static struct mkxp_sandbox::bindings::rb_data_type viewport_type;
     static VALUE viewport_class;
 
-    SANDBOX_COROUTINE(viewport_binding_init,
+    struct viewport_binding_init : boost::asio::coroutine {
         SANDBOX_DEF_ALLOC(viewport_type)
         SANDBOX_DEF_DFREE(Viewport)
 
         static VALUE initialize(int32_t argc, wasm_ptr_t argv, VALUE self) {
-            SANDBOX_COROUTINE(coro,
+            struct coro : boost::asio::coroutine {
                 Viewport *viewport;
                 int32_t x;
                 int32_t y;
@@ -74,7 +74,7 @@ namespace mkxp_sandbox {
 
                     return SANDBOX_NIL;
                 }
-            )
+            };
 
             return sb()->bind<struct coro>()()(argc, argv, self);
         }
@@ -93,7 +93,7 @@ namespace mkxp_sandbox {
         }
 
         static VALUE flash(VALUE self, VALUE obj, VALUE value) {
-            SANDBOX_COROUTINE(coro,
+            struct coro : boost::asio::coroutine {
                 int duration;
 
                 VALUE operator()(VALUE self, VALUE obj, VALUE value) {
@@ -104,7 +104,7 @@ namespace mkxp_sandbox {
 
                     return SANDBOX_NIL;
                 }
-            )
+            };
 
             return sb()->bind<struct coro>()()(self, obj, value);
         }
@@ -141,7 +141,7 @@ namespace mkxp_sandbox {
                 SANDBOX_INIT_PROP_BIND(viewport_class, z);
             }
         }
-    )
+    };
 }
 
 #endif // MKXPZ_SANDBOX_VIEWPORT_BINDING_H
diff --git a/binding-sandbox/window-binding.h b/binding-sandbox/window-binding.h
index fd8567de..386cc9df 100644
--- a/binding-sandbox/window-binding.h
+++ b/binding-sandbox/window-binding.h
@@ -31,12 +31,12 @@ namespace mkxp_sandbox {
     static struct mkxp_sandbox::bindings::rb_data_type window_type;
     static VALUE window_class;
 
-    SANDBOX_COROUTINE(window_binding_init,
+    struct window_binding_init : boost::asio::coroutine {
         SANDBOX_DEF_ALLOC(window_type)
         SANDBOX_DEF_DFREE(Window)
 
         static VALUE initialize(int32_t argc, wasm_ptr_t argv, VALUE self) {
-            SANDBOX_COROUTINE(coro,
+            struct coro : boost::asio::coroutine {
                 Window *window;
                 VALUE viewport_obj;
                 Viewport *viewport;
@@ -67,7 +67,7 @@ namespace mkxp_sandbox {
 
                     return SANDBOX_NIL;
                 }
-            )
+            };
 
             return sb()->bind<struct coro>()()(argc, argv, self);
         }
@@ -138,7 +138,7 @@ namespace mkxp_sandbox {
                 SANDBOX_INIT_PROP_BIND(window_class, contents_opacity);
             }
         }
-    )
+    };
 }
 
 #endif // MKXPZ_SANDBOX_WINDOW_BINDING_H
diff --git a/binding-sandbox/windowvx-binding.h b/binding-sandbox/windowvx-binding.h
index 80f75678..a0e93f9c 100644
--- a/binding-sandbox/windowvx-binding.h
+++ b/binding-sandbox/windowvx-binding.h
@@ -34,12 +34,12 @@ namespace mkxp_sandbox {
     static struct mkxp_sandbox::bindings::rb_data_type windowvx_type;
     static VALUE windowvx_class;
 
-    SANDBOX_COROUTINE(windowvx_binding_init,
+    struct windowvx_binding_init : boost::asio::coroutine {
         SANDBOX_DEF_ALLOC(windowvx_type)
         SANDBOX_DEF_DFREE(WindowVX)
 
         static VALUE initialize(int32_t argc, wasm_ptr_t argv, VALUE self) {
-            SANDBOX_COROUTINE(coro,
+            struct coro : boost::asio::coroutine {
                 WindowVX *window;
                 VALUE viewport_obj;
                 Viewport *viewport;
@@ -97,7 +97,7 @@ namespace mkxp_sandbox {
 
                     return SANDBOX_NIL;
                 }
-            )
+            };
 
             return sb()->bind<struct coro>()()(argc, argv, self);
         }
@@ -140,7 +140,7 @@ namespace mkxp_sandbox {
         SANDBOX_DEF_GFX_PROP_I(WindowVX, Openness, openness);
 
         static VALUE move(VALUE self, VALUE xv, VALUE yv, VALUE wv, VALUE hv) {
-            SANDBOX_COROUTINE(coro,
+            struct coro : boost::asio::coroutine {
                 WindowVX *window;
                 int32_t x;
                 int32_t y;
@@ -160,7 +160,7 @@ namespace mkxp_sandbox {
 
                     return SANDBOX_NIL;
                 }
-            )
+            };
 
             return sb()->bind<struct coro>()()(self, xv, yv, wv, hv);
         }
@@ -217,7 +217,7 @@ namespace mkxp_sandbox {
                 }
             }
         }
-    )
+    };
 }
 
 #endif // MKXPZ_SANDBOX_WINDOWVX_BINDING_H
diff --git a/libretro/sandbox-bindgen.rb b/libretro/sandbox-bindgen.rb
index e3cbf76d..90e2ce9c 100644
--- a/libretro/sandbox-bindgen.rb
+++ b/libretro/sandbox-bindgen.rb
@@ -616,11 +616,10 @@ File.readlines('tags', chomp: true).each do |line|
 
   coroutine_declaration = <<~HEREDOC
     struct #{func_name} : boost::asio::coroutine {
-        friend struct bindings::stack_frame_guard<struct #{func_name}>;
         #{coroutine_ret} operator()(#{declaration_args.join(', ')});
+        #{func_name}(struct binding_base &b);
         #{coroutine_destructor.empty? ? '' : "~#{func_name}();\n    "}private:
         struct binding_base &bind;
-        #{func_name}(struct binding_base &b);
     #{fields.empty? ? '' : fields.map { |field| "    #{field};\n" }.join}};
   HEREDOC
 
diff --git a/src/core.cpp b/src/core.cpp
index 454ba9da..abe7fb2f 100644
--- a/src/core.cpp
+++ b/src/core.cpp
@@ -223,13 +223,13 @@ static void audio_render(size_t samples) {
 }
 
 static VALUE func(VALUE arg) {
-    SANDBOX_COROUTINE(coro,
+    struct coro : boost::asio::coroutine {
         void operator()() {
             BOOST_ASIO_CORO_REENTER (this) {
                 SANDBOX_AWAIT(sandbox_binding_init);
             }
         }
-    )
+    };
 
     sb()->bind<struct coro>()()();
 
@@ -237,27 +237,27 @@ static VALUE func(VALUE arg) {
 }
 
 static VALUE rescue(VALUE arg, VALUE exception) {
-    SANDBOX_COROUTINE(coro,
+    struct coro : boost::asio::coroutine {
         void operator()(VALUE exception) {
             BOOST_ASIO_CORO_REENTER (this) {
                 SANDBOX_AWAIT(rb_eval_string, "puts 'Entered rescue()'");
                 SANDBOX_AWAIT(rb_p, exception);
             }
         }
-    )
+    };
 
     sb()->bind<struct coro>()()(exception);
 
     return arg;
 }
 
-SANDBOX_COROUTINE(main,
+struct main : boost::asio::coroutine {
     void operator()() {
         BOOST_ASIO_CORO_REENTER (this) {
             SANDBOX_AWAIT(rb_rescue2, func, SANDBOX_NIL, rescue, SANDBOX_NIL, sb()->rb_eException(), 0);
         }
     }
-)
+};
 
 static void deinit_sandbox() {
     shared_state_initialized = false;