diff --git a/src/os2/window.cpp b/src/os2/window.cpp
index d62acedc44..cb386ae1bc 100644
--- a/src/os2/window.cpp
+++ b/src/os2/window.cpp
@@ -1813,7 +1813,7 @@ MRESULT EXPENTRY wxWndProc(
     {
         if (pWnd)
             rc = pWnd->OS2WindowProc(ulMsg, wParam, lParam);
-        else
+        if(!rc)
             rc = ::WinDefWindowProc(hWnd, ulMsg, wParam, lParam);
     }
     return rc;