--- a/Tools__NewSystemBrowser.st	Mon Jan 21 15:11:20 2013 +0100
+++ b/Tools__NewSystemBrowser.st	Tue Jan 22 15:12:23 2013 +0100
@@ -44455,13 +44455,15 @@
             ].
             "look for majority protocol in subclasses"
             subclassCategories := Bag new.
-            mthd mclass allSubclassesDo:[:cls |
-                |redefined|
-
-                redefined := superClass compiledMethodAt:mthd selector.
-                redefined notNil ifTrue:[
-                    subclassCategories add:(redefined category).
-                ]
+            superClass notNil ifTrue:[    
+                mthd mclass allSubclassesDo:[:cls |
+                    |redefined|
+
+                    redefined := superClass compiledMethodAt:mthd selector.
+                    redefined notNil ifTrue:[
+                        subclassCategories add:(redefined category).
+                    ]
+                ].
             ].
             subclassCategories notEmpty ifTrue:[
                 subclassCategories := (subclassCategories valuesAndCounts 
@@ -58111,11 +58113,11 @@
 !NewSystemBrowser class methodsFor:'documentation'!
 
 version
-    ^ '$Header: /cvs/stx/stx/libtool/Tools__NewSystemBrowser.st,v 1.1830 2013-01-21 14:11:20 cg Exp $'
+    ^ '$Header: /cvs/stx/stx/libtool/Tools__NewSystemBrowser.st,v 1.1831 2013-01-22 14:12:23 cg Exp $'
 !
 
 version_CVS
-    ^ '$Header: /cvs/stx/stx/libtool/Tools__NewSystemBrowser.st,v 1.1830 2013-01-21 14:11:20 cg Exp $'
+    ^ '$Header: /cvs/stx/stx/libtool/Tools__NewSystemBrowser.st,v 1.1831 2013-01-22 14:12:23 cg Exp $'
 !
 
 version_SVN