win32ss/user/ntuser/window.c | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/win32ss/user/ntuser/window.c b/win32ss/user/ntuser/window.c
index 8e42d693d45..23c7c2c7b26 100644
--- a/win32ss/user/ntuser/window.c
+++ b/win32ss/user/ntuser/window.c
@@ -1623,6 +1623,7 @@ PWND FASTCALL IntCreateWindow(CREATESTRUCTW* Cs,
    PTHREADINFO pti = NULL;
    BOOL MenuChanged;
    BOOL bUnicodeWindow;
+   PCALLPROCDATA pcpd = NULL;
 
    pti = pdeskCreated ? gptiDesktopThread : GetW32ThreadInfo();
 
@@ -1769,7 +1770,16 @@ PWND FASTCALL IntCreateWindow(CREATESTRUCTW* Cs,
     see what problems this would cause. */
 
    // Set WndProc from Class.
-   pWnd->lpfnWndProc  = pWnd->pcls->lpfnWndProc;
+   if (IsCallProcHandle(pWnd->pcls->lpfnWndProc))
+   {
+       pcpd = UserGetObject(gHandleTable, pWnd->pcls->lpfnWndProc, TYPE_CALLPROC);
+       if (pcpd) pWnd->lpfnWndProc = pcpd->pfnClientPrevious;
+       pcpd = NULL;
+   }
+   else
+   {
+       pWnd->lpfnWndProc  = pWnd->pcls->lpfnWndProc;
+   }
 
    // GetWindowProc, test for non server side default classes and set WndProc.
     if ( pWnd->pcls->fnid <= FNID_GHOST && pWnd->pcls->fnid >= FNID_BUTTON )