There's File::Spec for doing this kind of thing portably. Most of the time, I just use slashes "as appropriate". Any path I have in a variable normally does not have a trailing slash. If it does, I consider that a special case, and it ends up eating part of my mind as I put effort into remembering it all the time. I suspect, however, that I just don't run into this kind of problem as often as you do, so I haven't come up with any practice that I'd swear by.