diff --git a/reactos/subsystems/win32/win32k/ntuser/winpos.c b/reactos/subsystems/win32/win32k/ntuser/winpos.c
index 7ab878b2006..2804204fbfa 100644
--- a/reactos/subsystems/win32/win32k/ntuser/winpos.c
+++ b/reactos/subsystems/win32/win32k/ntuser/winpos.c
@@ -1324,6 +1324,8 @@ co_WinPosShowWindow(PWINDOW_OBJECT Window, INT Cmd)
    ASSERT_REFS_CO(Window);
    Wnd = Window->Wnd;
 
+   if (!Wnd) return FALSE;
+   
    WasVisible = (Wnd->Style & WS_VISIBLE) != 0;
 
    switch (Cmd)