This is not an issue with GTDebugger, but the way opal generates the tempvar index or the way, debuggerMap tries to access the context vars 17660 <https://pharo.fogbugz.com/f/cases/17660/wrong-tempvar-values-in-debugger> wrong tempvar values in debugger This is a really special case, I wasn't able yet to create an easier example for reproducing this bug: - put a self haltOnce in RAbstractClass>>#directlyDefinesLocalMethod: - enable halt once - select any other method in Nautilus and choose "Rename method (all)" from method panes context menu - enter a new name and push "OK" -> the debugger pops up in method directlyDefinesLocalMethod: - select the first "allClassesDo:" context from top of the stack -> the debugger shows that we are in the evalBlock context The "seen" variable is a Set, but if you look at the "Variables"-pane, it is shown as a block (this is actually the parameter aBlock)