Not too long ago it was reported that Matthew Fox and Ed Harris had joined Brad Pitt on the cast of World War Z, the post–apocalyptic zombie movie told from the perspectives of some of those fighting to survive, which is based on the Max Brooks book of the same name.

As things tend to go from time to time in good ol’ Hollywood, these castings haven’t exactly worked out. Vulture is reporting that Fox has decided not to appear in the movie due to a scheduling conflict with the Tyler Perry–starring I, Alex Cross. As for Harris, it’s currently unclear why the actor was unable to take the job.

That leaves Paramount Pictures in a rush to try and find two actors to replace Fox and Harris after things didn’t work out…which is a bit strange—one would think that any scheduling conflicts would have been known much sooner than this.

In any case, filming on World War Z has already begun, so expect to hear about two new actors being cast very soon.

Paramount is currently checking out potential actors in both Los Angeles and London.