Index: dll/win32/user32/windows/message.c
===================================================================
--- dll/win32/user32/windows/message.c	(revision 40964)
+++ dll/win32/user32/windows/message.c	(working copy)
@@ -1709,7 +1709,7 @@
 PostQuitMessage(
   int nExitCode)
 {
-  (void) NtUserPostMessage(NULL, WM_QUIT, nExitCode, 0);
+  (VOID)NtUserCallOneParam(nExitCode, ONEPARAM_ROUTINE_POSTQUITMESSAGE)
 }
 
 
Index: subsystems/win32/win32k/ntuser/simplecall.c
===================================================================
--- subsystems/win32/win32k/ntuser/simplecall.c	(revision 40964)
+++ subsystems/win32/win32k/ntuser/simplecall.c	(working copy)
@@ -152,6 +152,13 @@
 
    switch(Routine)
    {
+      case ONEPARAM_ROUTINE_POSTQUITMESSAGE:
+          {
+                PTHREADINFO pti;
+                pti = PsGetCurrentThreadWin32Thread();
+                MsqPostQuitMessage(pti->MessageQueue, Param);
+                RETURN(TRUE);
+          }
       case ONEPARAM_ROUTINE_SHOWCURSOR:
          RETURN( (DWORD)UserShowCursor((BOOL)Param) );