diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/index/composite/cpp/CPPCompositesFactory.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/index/composite/cpp/CPPCompositesFactory.java
index 5e5f16ea904..4aff3b0b195 100644
--- a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/index/composite/cpp/CPPCompositesFactory.java
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/index/composite/cpp/CPPCompositesFactory.java
@@ -274,7 +274,7 @@ public class CPPCompositesFactory extends AbstractCompositeFactory {
 			return rtype;
 		} 
 		
-		throw new CompositingNotImplementedError();
+		throw new CompositingNotImplementedError(rtype.getClass().getName());
 	}
 	
 	public ICPPEvaluation getCompositeEvaluation(ICPPEvaluation eval) {
@@ -553,7 +553,7 @@ public class CPPCompositesFactory extends AbstractCompositeFactory {
 			return e;
 		}
 		
-		throw new CompositingNotImplementedError();
+		throw new CompositingNotImplementedError(eval.getClass().getName());
 	}
 
 	private ICPPEvaluation[] getCompositeEvaluationArray(ICPPEvaluation[] array) {