Yes, if you know that the process is going to exit. In this case, the missing free is in a function which is about a dozen calls down in the stack, and I know that it's harmless right now because I've looked at the code and verified that an error there will always result in tarsnap exiting; but if I don't fix this now it's quite possible that in the future I'll have code which uses that function but can tolerate it failing.