Hello during the build of propellor, I can see this error find . | grep -v /.git/ | grep -v /tmp/ | grep -v /dist/ | grep -v /doc/ | egrep '\.hs$' | xargs hothasktags | perl -ne 'print; s/Propellor\.Property\.//; print' | sort > tags 2>/dev/null || true xargs: hothasktags: No such file or directory Don't you think that a build-dep is missing ?