I fixed some of the style issues mentioned on appspot. (I was not sure about some of them and responded to them in appspot comments). Also sigHandler became sighandler for consistency with the rest of pdb.py. The new version of the patch is attached. However, it appears that I've been a bit over-optimistic about the lack of side-effects. In particular, the patch results in an very ugly error message when Ctrl-C is pressed while at pdb prompt.. *** AttributeError: AttributeError("'NoneType' object has no attribute 'f_globals'",) Everything still seems to be working, but it's definitely ugly (and behaves differently on Windows and Linux). I will try to summarize possible Ctrl-C scenarios in a separate post