Should be fine. If you're unsure, take a snip of film like a leader from some 35mm, put it in the fixer and see how long it takes to clear, and then fix the real film for twice that time.

At times I've used the same batch of fixer for both printing and negs, but now I keep separate batches to prevent staining of prints from antihalation dyes that come out of film, pyro stain, and such. That's not a concern, though, if you're using fixer from printing for film.