Changing manifest values in RPM built with FPM

I'm using the delightfully–named Effing Package Manager (FPM) to build RPMs and DEBs for a project. After publishing the generated RPM with createrepo, I noted the following lines in the generated repo UUID-primary.xml.gz: [..] me@machine-that-built-this machine-that-built-this [..] Short of changing my hostname and user, is there a way to define these with FPM? I've got plenty of experience building and running DEB repos, this is my first attempt at RPMs.