diff --git a/win32ss/user/ntuser/defwnd.c b/win32ss/user/ntuser/defwnd.c
index 81ece247b78..a5c230df5b0 100644
--- a/win32ss/user/ntuser/defwnd.c
+++ b/win32ss/user/ntuser/defwnd.c
@@ -797,6 +797,11 @@ IntDefWindowProc(
             HWND hwndTop = UserGetForegroundWindow();
             PWND topWnd = UserGetWindowObject(hwndTop);
 
+            /* MS Doc: The foreground window can be NULL in certain circumstances,
+               such as when a window is losing activation */
+            if (!topWnd)
+               return 0;
+
             // We want to forbid snapping operations on the TaskBar
             // We use a heuristic for detecting the TaskBar Wnd by its typical Style & ExStyle Values
             ExStyleTB = (topWnd->ExStyle & WS_EX_TOOLWINDOW);
@@ -805,7 +810,7 @@ IntDefWindowProc(
                         && (ExStyleTB == WS_EX_TOOLWINDOW);
             TRACE("ExStyle=%x Style=%x IsTaskBar=%d\n", ExStyleTB, StyleTB, IsTaskBar);
 
-            if (topWnd && !IsTaskBar)
+            if (!IsTaskBar)
             {
                if ((topWnd->style & WS_THICKFRAME) == 0)
                   return 0;