diff --git a/include/wx/msw/ole/comimpl.h b/include/wx/msw/ole/comimpl.h
index 3d21bff916..3f8b1c7996 100644
--- a/include/wx/msw/ole/comimpl.h
+++ b/include/wx/msw/ole/comimpl.h
@@ -39,6 +39,9 @@ extern WXDLLIMPEXP_CORE bool IsIidFromList(REFIID riid, const IID *aIids[], size
 // ============================================================================
 
 /*
+   WARNING: This does NOT work with multiple inheritance, so multiple
+   interfaces can only be supported when they inherit from each other.
+
    The most dumb implementation of IUnknown methods. We don't support
    aggregation nor containment, but for 99% of cases this simple
    implementation is quite enough.