diff --git a/core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/core/parser/tests/ast2/AST2CPPTests.java b/core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/core/parser/tests/ast2/AST2CPPTests.java
index a0fadad9363..422ffa7f1c9 100644
--- a/core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/core/parser/tests/ast2/AST2CPPTests.java
+++ b/core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/core/parser/tests/ast2/AST2CPPTests.java
@@ -11870,6 +11870,19 @@ public class AST2CPPTests extends AST2TestBase {
 		assertTrue(test.getType() instanceof IProblemType); // resolution is ambiguous
 	}
 	
+	//	namespace N {
+	//	    class Color {};
+	//	    Color operator"" _color(const char*, unsigned long);
+	//	}
+	//	void setColor(N::Color);
+	//	int main() {
+	//	    using namespace N;
+	//	    setColor("#ffffff"_color);  // ERROR
+	//	}
+	public void testUserDefinedLiteralInNamespace_510665() throws Exception {
+		parseAndCheckBindings();
+	}
+	
 	//	double waldo1 = 02.968;
 	//	double waldo2 = 09.268;
 	//	double waldo3 = 02e2;
diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/cpp/semantics/CPPSemantics.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/cpp/semantics/CPPSemantics.java
index 4a301a5ecf7..6ce4dd118b9 100644
--- a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/cpp/semantics/CPPSemantics.java
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/cpp/semantics/CPPSemantics.java
@@ -3181,7 +3181,8 @@ public class CPPSemantics {
 		 *
 		 */
 		int kind = exp.getKind();
-		IBinding[] bindings = findBindings(exp.getTranslationUnit().getScope(), ((CPPASTLiteralExpression) exp).getOperatorName(), false);
+		IScope lookupScope = CPPVisitor.getContainingScope(exp);
+		IBinding[] bindings = findBindings(lookupScope, ((CPPASTLiteralExpression) exp).getOperatorName(), false);
 		ICPPFunction[] funcs = new ICPPFunction[bindings.length];
 		ICPPFunctionTemplate[] tplFunctions = new ICPPFunctionTemplate[bindings.length];
 		LookupData data = new LookupData(((CPPASTLiteralExpression) exp).getOperatorName(), null, exp);