I created zmq20 because mongrel2 1.5.x needed 2.0.x version of zeromq to build. Now the update mongrel2 source builds fine with zmq and I'd suggest to fade out zmq20 replaced_by'ing it with zmq that sports version 2.1.11 . There's a pending upcoming 3.x zeromq with incompatible API, what will 2.1.11 be called when 3 will become available, zmq21? -- Andrea