diff --git a/ICSharpCode.NRefactory.CSharp/Completion/CompletionDataWrapper.cs b/ICSharpCode.NRefactory.CSharp/Completion/CompletionDataWrapper.cs
index b0dd18918a..16368ae4fe 100644
--- a/ICSharpCode.NRefactory.CSharp/Completion/CompletionDataWrapper.cs
+++ b/ICSharpCode.NRefactory.CSharp/Completion/CompletionDataWrapper.cs
@@ -80,7 +80,7 @@ namespace ICSharpCode.NRefactory.CSharp.Completion
 			result.Add (Factory.CreateLiteralCompletionData (alias));
 		}
 
-		Dictionary<IType, ICompletionData> usedTypes = new Dictionary<IType, ICompletionData> ();
+		Dictionary<string, ICompletionData> usedTypes = new Dictionary<string, ICompletionData> ();
 
 		public ICompletionData AddType(IType type, bool showFullName, bool isInAttributeContext = false)
 		{
@@ -93,14 +93,16 @@ namespace ICSharpCode.NRefactory.CSharp.Completion
 			if (def != null && def.ParentAssembly != completion.ctx.CurrentAssembly && !def.IsBrowsable())
 				return null;
 			ICompletionData usedType;
-			if (usedTypes.TryGetValue (type, out usedType)) {
-				usedType.AddOverload (Factory.CreateTypeCompletionData(type, showFullName, isInAttributeContext));
+			var data = Factory.CreateTypeCompletionData(type, showFullName, isInAttributeContext);
+			var text = data.DisplayText;
+
+			if (usedTypes.TryGetValue(text, out usedType)) {
+				usedType.AddOverload(data);
 				return usedType;
 			} 
-			var iCompletionData = Factory.CreateTypeCompletionData(type, showFullName, isInAttributeContext);
-			usedTypes[type] = iCompletionData;
-			result.Add(iCompletionData);
-			return iCompletionData;
+			usedTypes [text] = data;
+			result.Add(data);
+			return data;
 		}
 
 		Dictionary<string, List<ICompletionData>> data = new Dictionary<string, List<ICompletionData>> ();