diff --git a/dlls/user32/user_main.c b/dlls/user32/user_main.c
index 007cb687f5d..830097570a2 100644
--- a/dlls/user32/user_main.c
+++ b/dlls/user32/user_main.c
@@ -55,6 +55,10 @@ static DWORD exiting_thread_id;
 
 extern void WDML_NotifyThreadDetach(void);
 
+#ifdef __MINGW32__
+/* work around a Mingw build issue where _wassert causes a duplicate reference to MessageBoxW */
+void __cdecl _wassert( const WCHAR *msg, const WCHAR *file, unsigned line) { abort(); }
+#endif
 
 /***********************************************************************
  *           USER_Lock