diff -ruN /tmp/sos-code-article9/sos/ksynch.c ../sos-code-article9/sos/ksynch.c
--- /tmp/sos-code-article9/sos/ksynch.c	2005-12-28 11:44:57.000000000 +0100
+++ ../sos-code-article9/sos/ksynch.c	2006-01-01 17:48:09.000000000 +0100
@@ -223,10 +237,12 @@
        *   mutex->owner = thread_that_is_woken_up;
        * But the real Id of the next thread owning the mutex is not
        * that important. What is important here is that mutex->owner
-       * IS NOT NULL. Otherwise there will be a possibility for the
-       * thread woken up here to have the mutex stolen by a thread
-       * locking the mutex in the meantime.
+       * IS NOT NULL and does not correspond to any existing
+       * thread. Otherwise there will be a possibility for the thread
+       * woken up here to have the mutex stolen by a thread locking
+       * the mutex in the meantime.
        */
+      mutex->owner = 0x43;
       retval = sos_kwaitq_wakeup(& mutex->kwaitq, 1, SOS_OK);
     }