diff --git a/src/msw/frame.cpp b/src/msw/frame.cpp
index ed3369c64c..c9c90a78c7 100644
--- a/src/msw/frame.cpp
+++ b/src/msw/frame.cpp
@@ -57,6 +57,12 @@
     #include "wx/univ/colschem.h"
 #endif // __WXUNIVERSAL__
 
+// FIXME-VC6: Only VC6 doesn't have this in its standard headers so this
+//            could be removed once support for it is dropped.
+#ifndef WM_UNINITMENUPOPUP
+    #define WM_UNINITMENUPOPUP 0x0125
+#endif
+
 // ----------------------------------------------------------------------------
 // globals
 // ----------------------------------------------------------------------------