diff --git a/include/wx/msw/window.h b/include/wx/msw/window.h
index d83616333a..b383926a46 100644
--- a/include/wx/msw/window.h
+++ b/include/wx/msw/window.h
@@ -386,7 +386,6 @@ public:
   // Do Update UI processing for controls
   void UpdateWindowUI(void);
 
-  void OnSize(wxSizeEvent& event);
   void OnEraseBackground(wxEraseEvent& event);
   void OnChar(wxKeyEvent& event);
   void OnPaint(wxPaintEvent& event);