diff --git a/reactos/ntoskrnl/ps/kill.c b/reactos/ntoskrnl/ps/kill.c
index 3b020d46c07..b1da4ed6910 100644
--- a/reactos/ntoskrnl/ps/kill.c
+++ b/reactos/ntoskrnl/ps/kill.c
@@ -1,4 +1,4 @@
-/* $Id: kill.c,v 1.74 2004/08/31 20:17:18 hbirr Exp $
+/* $Id: kill.c,v 1.75 2004/09/14 18:37:40 gvg Exp $
  *
  * COPYRIGHT:       See COPYING in the top level directory
  * PROJECT:         ReactOS kernel
@@ -124,6 +124,15 @@ PsTerminateCurrentThread(NTSTATUS ExitStatus)
    CurrentThread = PsGetCurrentThread();
    CurrentProcess = CurrentThread->ThreadsProcess;
 
+   /* Can't terminate a thread if it attached another process */
+   if (AttachedApcEnvironment == CurrentThread->Tcb.ApcStateIndex)
+     {
+        KEBUGCHECKEX(INVALID_PROCESS_ATTACH_ATTEMPT, (ULONG) CurrentProcess,
+                     (ULONG) CurrentThread->Tcb.ApcState.Process,
+                     (ULONG) CurrentThread->Tcb.ApcStateIndex,
+                     (ULONG) CurrentThread);
+     }
+
    KeAcquireSpinLock(&PiThreadListLock, &oldIrql);
 
    DPRINT("terminating %x\n",CurrentThread);