diff --git a/include/wx/msw/dib.h b/include/wx/msw/dib.h
index 1e19b76b6c..2944272aaf 100644
--- a/include/wx/msw/dib.h
+++ b/include/wx/msw/dib.h
@@ -12,6 +12,9 @@
 #ifndef _WX_DIB_H_
 #define _WX_DIB_H_
 
+class WXDLLEXPORT wxBitmap;
+class WXDLLEXPORT wxColourMap;
+
 // Save (device dependent) wxBitmap as a DIB
 bool             wxSaveBitmap(wxChar *filename, wxBitmap *bitmap, wxColourMap *colourmap = NULL);