diff --git a/reactos/win32ss/user/ntuser/winsta.c b/reactos/win32ss/user/ntuser/winsta.c
index 9bf8bdfeafb..18aebdac6c4 100644
--- a/reactos/win32ss/user/ntuser/winsta.c
+++ b/reactos/win32ss/user/ntuser/winsta.c
@@ -933,7 +933,7 @@ UserSetProcessWindowStation(HWINSTA hWindowStation)
 
    ppi->prpwinsta = NewWinSta;
    ppi->hwinsta = hWindowStation;
-   ppi->amwinsta = ObjectHandleInfo.GrantedAccess;
+   ppi->amwinsta = hWindowStation != NULL ? ObjectHandleInfo.GrantedAccess : 0;
    ERR("WS : Granted Access %p\n",ppi->amwinsta);
 
    if (RtlAreAllAccessesGranted(ppi->amwinsta, WINSTA_READSCREEN))