Can't connect from OSX to FreeBSD with mosh

I've installed mosh on my laptop using Macports and on my FreeBSD server using ports. Whenever I try to connect to my server I get the following error:

Password for xxxxxx@xxx.xxx.xx.xx:
zsh:1: command not found: mosh-server
Connection to xxx.xxx.xx.xx closed.
/opt/local/bin/mosh: Did not find mosh server startup message.

I can't find any binaries on my BSD box called mosh-server with whereis.