I had the strangest problem yesterday in #40528 Define a class: Object subclass: #AAA instanceVariableNames: 'five four one three two' classVariableNames: '' category: '_UnpackagedPackage' With one method: initialize super initialize. one := 1. two := 2. three := 3. four := 4. five := 5 Open a playground and do it & go an instance: AAA new In the raw tab execute: self class allInstVarNames collect: [ :each | each -> (self instVarNamed: each) ]. Which gives you, as expected: {#five->5. #four->4. #one->1. #three->3. #two->2} Now auto generate one accessor, say for one. Play again, and now the result is: {#five->1. #four->2. #one->3. #three->4. #two->5} !? Reaccepting the class definition fixes the problem. Sven PS: this code is used by STON, NeoJSON & NeoCSV.