diff --git a/include/wx/os2/frame.h b/include/wx/os2/frame.h
index f8bd78661c..48120d8643 100644
--- a/include/wx/os2/frame.h
+++ b/include/wx/os2/frame.h
@@ -217,6 +217,8 @@ private:
     DECLARE_DYNAMIC_CLASS(wxFrame)
 };
 
+MRESULT EXPENTRY wxFrameWndProc(HWND  hWnd,ULONG ulMsg, MPARAM wParam, MPARAM lParam);
+MRESULT EXPENTRY wxFrameMainWndProc(HWND  hWnd,ULONG ulMsg, MPARAM wParam, MPARAM lParam);
 #endif
     // _WX_FRAME_H_