Before I recognized that Adrian fixed the ObjectFinalizerTests>>testFinalizationOfEquals I gave it try myself. I came to the same conclusion as Adrian how to fix. But now after knowing how it works I do not know why the test succeeds :) The test uses 1 to: 5 do: [:n | o := Object new. bag add: n. o toFinalizeSend: #remove: to: bag with: n]. 1 to: 5 do: [:n | o := Object new. bag add: n. o toFinalizeSend: #remove: to: bag with: n]. My problem is that toFinalizeSend:to:with adds an Objectfinalizer to the finalizationRegistry of the instance. But Object>>finalizationRegistry "Answer the finalization registry associated with the receiver." ^WeakRegistry default returns a global object which is WeakKeyDictionary. And | d | d := WeakKeyDictionary new. d at: (1 asString copy) put: $a. d at: (1 asString copy) put: $b. d size prints 1. To me that would exchange every entry from the first run by the second run (because the objects are equal). So I would assume that if there does not happen a run of the garbagecollector between the two loops the objects of the first loop should be still contained in the bag. But the test is named finalizationOfEquals so I have to assume: self doesNotUnderstand Can someone explain it to me, please? Norbert