[root@PAUMAKA /usr/ports/audio/nas]# make install clean
===>   nas-1.8 depends on executable in : imake - found
===>   nas-1.8 depends on shared library: X11.6 - found
===>  Configuring for nas-1.8
env: xmkmf: No such file or directory
*** Error code 127

Stop in /usr/ports/audio/nas.
[root@PAUMAKA /usr/ports/audio/nas]# make deinstall
===>  Deinstalling for audio/nas
===>   nas not installed, skipping
[root@PAUMAKA /usr/ports/audio/nas]# make install
===>   nas-1.8 depends on executable in : imake - found
===>   nas-1.8 depends on shared library: X11.6 - found
===>  Configuring for nas-1.8
env: xmkmf: No such file or directory
*** Error code 127

Stop in /usr/ports/audio/nas.