diff --git a/mps/code/global.c b/mps/code/global.c
index ca0946ae9af..0bf481cb136 100644
--- a/mps/code/global.c
+++ b/mps/code/global.c
@@ -1,7 +1,7 @@
 /* global.c: ARENA-GLOBAL INTERFACES
  *
  * $Id$
- * Copyright (c) 2001-2013 Ravenbrook Limited.  See end of file for license.
+ * Copyright (c) 2001-2014 Ravenbrook Limited.  See end of file for license.
  * Portions copyright (C) 2002 Global Graphics Software.
  *
  * .sources: See <design/arena/>.  design.mps.thread-safety is relevant
@@ -441,20 +441,23 @@ void GlobalsPrepareToDestroy(Globals arenaGlobals)
   Arena arena;
   TraceId ti;
   Trace trace;
+  Chain defaultChain;
 
   AVERT(Globals, arenaGlobals);
 
   arena = GlobalsArena(arenaGlobals);
   arenaDenounce(arena);
 
-  ChainDestroy(arenaGlobals->defaultChain);
+  defaultChain = arenaGlobals->defaultChain;
   arenaGlobals->defaultChain = NULL;
+  ChainDestroy(defaultChain);
 
   LockReleaseMPM(arenaGlobals->lock);
   /* Theoretically, another thread could grab the lock here, but it's */
   /* not worth worrying about, since an attempt after the lock has been */
   /* destroyed would lead to a crash just the same. */
   LockFinish(arenaGlobals->lock);
+  arenaGlobals->lock = NULL;
 
   TRACE_SET_ITER(ti, trace, TraceSetUNIV, arena)
     /* <design/message-gc/#lifecycle> */
@@ -1140,7 +1143,7 @@ Bool ArenaEmergency(Arena arena)
 
 /* C. COPYRIGHT AND LICENSE
  *
- * Copyright (C) 2001-2013 Ravenbrook Limited <http://www.ravenbrook.com/>.
+ * Copyright (C) 2001-2014 Ravenbrook Limited <http://www.ravenbrook.com/>.
  * All rights reserved.  This is an open source license.  Contact
  * Ravenbrook for commercial licensing options.
  * 
diff --git a/mps/code/traceanc.c b/mps/code/traceanc.c
index a383d71955c..675e18e1f95 100644
--- a/mps/code/traceanc.c
+++ b/mps/code/traceanc.c
@@ -1,7 +1,7 @@
 /* traceanc.c: ANCILLARY SUPPORT FOR TRACER
  *
  * $Id$
- * Copyright (c) 2001-2013 Ravenbrook Limited.
+ * Copyright (c) 2001-2014 Ravenbrook Limited.
  * See end of file for license.
  * Portions copyright (C) 2002 Global Graphics Software.
  *
@@ -239,8 +239,8 @@ void TracePostStartMessage(Trace trace)
     traceStartWhyToTextBuffer(tsMessage->why,
                               sizeof tsMessage->why, trace->why);
 
-    MessagePost(arena, TraceStartMessageMessage(tsMessage));
     arena->tsMessage[ti] = NULL;
+    MessagePost(arena, TraceStartMessageMessage(tsMessage));
   } else {
     arena->droppedMessages += 1;
   }
@@ -406,8 +406,8 @@ void TracePostMessage(Trace trace)
     tMessage->condemnedSize = trace->condemned;
     tMessage->notCondemnedSize = trace->notCondemned;
 
-    MessagePost(arena, TraceMessageMessage(tMessage));
     arena->tMessage[ti] = NULL;
+    MessagePost(arena, TraceMessageMessage(tMessage));
   } else {
     arena->droppedMessages += 1;
   }
@@ -479,10 +479,11 @@ Res TraceIdMessagesCreate(Arena arena, TraceId ti)
 
   traceStartMessageInit(arena, tsMessage);
   AVERT(TraceStartMessage, tsMessage);
-  arena->tsMessage[ti] = tsMessage;
 
   traceMessageInit(arena, tMessage);
   AVERT(TraceMessage, tMessage);
+
+  arena->tsMessage[ti] = tsMessage;
   arena->tMessage[ti] = tMessage;
   
   AVER(TraceIdMessagesCheck(arena, ti));
@@ -793,7 +794,7 @@ static void arenaForgetProtection(Globals globals)
 
 /* C. COPYRIGHT AND LICENSE
  *
- * Copyright (C) 2001-2013 Ravenbrook Limited
+ * Copyright (C) 2001-2014 Ravenbrook Limited
  * <http://www.ravenbrook.com/>.
  * All rights reserved.  This is an open source license.  Contact
  * Ravenbrook for commercial licensing options.