Hi 1) I'm working on an issue related to compact classes index and I discovered that behaviours implement #becomeCompactSimplyAt:, which has this comment: "Make me compact, but don't update the instances. *For importing segments* ." This made me think that it's no longer needed in the image since we removed ImageSegment. In other hand, I don't know why sender might decide if the instances of the class must be updated or not... do you? 2) The only users in Pharo 3 are in: Integer class >> initialize "Integer initialize" "Ensure we have the right compact class index" "LPI has been a compact class forever - just ensure basic correctness" (LargePositiveInteger indexIfCompact = 5) ifFalse:[ (Smalltalk compactClassesArray at: 5) ifNil:[LargePositiveInteger becomeCompactSimplyAt: 5] ifNotNil:[self error: 'Unexpected compact class setup']]. (LargeNegativeInteger indexIfCompact = 4) ifFalse:[ (Smalltalk compactClassesArray at: 4) ifNil:[LargeNegativeInteger becomeCompactSimplyAt: 4] ifNotNil:[self error: 'Unexpected compact class setup']]. Now, looking for other users of #indexIfCompact, I see that here is the only place in the image where compact indexes are checked/fixed. 3) I wonder if we should remove both #becomeCompactSimplyAt: and Integer class>>initialize. Thank you in advance. MartÃn