I tried building ZeroMQ with PGM support, enabling the use-flag did not work for me. After changing the ebuild file to allow for a 'configure --with-pgm', it turns out to have openpgm as dependency (which does not exist in tree). Reproducible: Always Steps to Reproduce: 1. Enable 'pgm' use-flag 2. emerge zeromq 3. No support for pgm is available Actual Results: No support for pgm is available Expected Results: Support for pgm is available After some more digging I found at the openpgm package was removed from Gentoo. I was able to get a working version of ZeroMQ with PGM after compiling the sources from - https://github.com/steve-o/openpgm.git (and moving some files around) It would be nice to have the package back, but I realize this might not be possible.