Thank you very much for your prompt response. Indeed, I did use an Exception::Class in my original script, just stripped all that off in order to expose the problem. I would assume like you that the Exception::Class should manage its instances coming from different directions and somehow merging one into another. Perhaps that class fails to treat/check $@ appropriately, but stringifies it too early when explicitly passed to the Exception thrower (in our example, that'd be pointless, hence ...). But it's just a spontaneous unverified notion. P.S.: Conway's Best Practices is like a bible for me, too. But while the (Christian) Bible is said to contain passages that pour many litres of blood, it is obvious that murderers are still a very minority, even among catholics I reckon.