diff --git a/src/AST/TypeExtensions.cs b/src/AST/TypeExtensions.cs
index 7570dc45..9165713f 100644
--- a/src/AST/TypeExtensions.cs
+++ b/src/AST/TypeExtensions.cs
@@ -10,7 +10,7 @@
 
         public static bool IsPrimitiveType(this Type t, out PrimitiveType primitive)
         {
-            var builtin = t as BuiltinType;
+            var builtin = t.Desugar() as BuiltinType;
             if (builtin != null)
             {
                 primitive = builtin.Type;
diff --git a/tests/Basic/Basic.h b/tests/Basic/Basic.h
index 01860bf0..d247bf0f 100644
--- a/tests/Basic/Basic.h
+++ b/tests/Basic/Basic.h
@@ -303,9 +303,12 @@ struct EmptyNamedNestedEnum
     enum { Value = 10 };
 };
 
-
+typedef unsigned long foo_t;
 typedef struct SomeStruct
 {
+	const foo_t& operator[](int i) const { return p[i]; }
+	foo_t& operator[](int i) { return p[i]; }
+	foo_t* p;
 }
 SomeStruct;