Updates: Status: WontFix Comment #1 on issue 3799 by marianopeck: CompiledMethod equality http://code.google.com/p/pharo/issues/detail?id=3799 yes, it is. I have already suffered that. Use IdentityDictionary or similar instead ;) Check this: http://forum.world.st/problem-with-CompiledMethod-equality-td2221276.html Summary: from my point of view, it is correct: the COMPILED method is equal. It doesn't matter wheter they come from (in which class they are). Notice that the name is CompiledMethod, and not Method. So, I think it is correct as it is. Of course, I realised this after all that long thread ;)