diff --git a/include/wx/defs.h b/include/wx/defs.h
index 475e18f5d7..0b8b502b7a 100644
--- a/include/wx/defs.h
+++ b/include/wx/defs.h
@@ -2839,35 +2839,8 @@ typedef const void* WXWidget;
 /*  included before or after wxWidgets classes, and therefore must be */
 /*  disabled here before any significant wxWidgets headers are included. */
 #ifdef __WXMSW__
-#ifdef GetClassInfo
-#undef GetClassInfo
-#endif
-
-#ifdef GetClassName
-#undef GetClassName
-#endif
-
-#ifdef DrawText
-#undef DrawText
-#endif
-
-#ifdef GetCharWidth
-#undef GetCharWidth
-#endif
-
-#ifdef StartDoc
-#undef StartDoc
-#endif
-
-#ifdef FindWindow
-#undef FindWindow
-#endif
-
-#ifdef FindResource
-#undef FindResource
-#endif
-#endif
-  /*  __WXMSW__ */
+#include "wx/msw/winundef.h"
+#endif /*  __WXMSW__ */
 
 /*  --------------------------------------------------------------------------- */
 /*  macro to define a class without copy ctor nor assignment operator */