--- a/MessageTracer.st	Sat Jun 29 13:27:38 2013 +0200
+++ b/MessageTracer.st	Sun Jun 30 10:11:02 2013 +0200
@@ -2144,7 +2144,7 @@
         definingClass withAllSuperclassesDo:[:aClass |
             aClass methodDictionary keys addAllTo:selectors
         ].
-        idx := anObject class instVarOffsetOf:anInstVarOrOffset.
+        idx := anObject class instVarIndexFor:anInstVarOrOffset.
         self 
             trapModificationsIn:anObject selectors:selectors filter:[:old :new | (old instVarAt:idx) ~~ (new instVarAt:idx)]
    ]
@@ -3349,7 +3349,7 @@
 !MessageTracer class methodsFor:'documentation'!
 
 version_CVS
-    ^ '$Header: /cvs/stx/stx/libbasic3/MessageTracer.st,v 1.124 2013-06-20 11:18:06 cg Exp $'
+    ^ '$Header: /cvs/stx/stx/libbasic3/MessageTracer.st,v 1.125 2013-06-30 08:11:02 cg Exp $'
 ! !