diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/cpp/semantics/AccessContext.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/cpp/semantics/AccessContext.java
index 115d40257b1..4b111b51fa8 100644
--- a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/cpp/semantics/AccessContext.java
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/cpp/semantics/AccessContext.java
@@ -286,6 +286,9 @@ public class AccessContext {
 		if (maxdepth > 0) {
 			for (ICPPBase cppBase : ClassTypeHelper.getBases(derived, point)) {
 				IBinding base= cppBase.getBaseClass();
+				if (base instanceof ICPPSpecialization) {
+					base = ((ICPPSpecialization) base).getSpecializedBinding();
+				}
 				if (base instanceof ICPPClassType) {
 					ICPPClassType tbase= (ICPPClassType) base;
 					if (tbase.isSameType(target)) {
diff --git a/core/org.eclipse.cdt.ui.tests/ui/org/eclipse/cdt/ui/tests/text/contentassist2/CompletionTests.java b/core/org.eclipse.cdt.ui.tests/ui/org/eclipse/cdt/ui/tests/text/contentassist2/CompletionTests.java
index a2ee3172027..d6663d6a837 100644
--- a/core/org.eclipse.cdt.ui.tests/ui/org/eclipse/cdt/ui/tests/text/contentassist2/CompletionTests.java
+++ b/core/org.eclipse.cdt.ui.tests/ui/org/eclipse/cdt/ui/tests/text/contentassist2/CompletionTests.java
@@ -735,6 +735,25 @@ public class CompletionTests extends AbstractContentAssistTest {
 		assertCompletionResults(fCursorOffset, expected, REPLACEMENT);
 	}
 
+	//	template<typename T>
+	//	struct Parent {
+	//	protected:
+	//		struct Nested {
+	//		protected:
+	//			using TParam = T;
+	//		};
+	//	};
+	//	
+	//	struct NestingTest: Parent<int> {
+	//		struct A : Nested {
+	//			TP/*cursor*/
+	//		};
+	//	};
+	public void testNestedBaseTemplateMembers_422401() throws Exception {
+		final String[] expected = { "TParam" };
+		assertCompletionResults(fCursorOffset, expected, ID);
+	}
+
 	//	struct A {};
 	//
 	//	template<typename T>