--- a/Tools__MethodCategoryList.st	Fri Feb 24 17:23:14 2017 +0100
+++ b/Tools__MethodCategoryList.st	Sat Feb 25 19:37:37 2017 +0100
@@ -917,6 +917,8 @@
              packages remainingClasses remainingCategories classesAlreadyDone 
              catListed showChanged|
 
+            leafClasses remove:nil ifAbsent:[]. "/ may happen when hierarchies are changed elsewhere.
+            
             (leafClasses size > 0 and:[protocols size > 0]) ifTrue:[
                 allProtocols := protocols includes:(self class nameListEntryForALL).
                 superSendProtocols := protocols includes:(self class nameListEntryForSuperSend).
@@ -1140,7 +1142,7 @@
       ]
 
     "Created: / 05-02-2000 / 13:42:10 / cg"
-    "Modified: / 18-09-2011 / 12:51:45 / cg"
+    "Modified: / 25-02-2017 / 18:34:28 / cg"
 ! !
 
 !MethodCategoryList methodsFor:'private'!