Are you using bash? It works fine for me.
```bash
~/pathfinder $ echo $PATH
/home/john/bin:/usr/sbin:/sbin:/home/john/pathfinder/st/bin:/usr/local/bin:/usr/bin:/bin:/usr/local/games:/usr/games:.
~/pathfinder $ pathfinder -x dist out
~/pathfinder $ echo $PATH
/home/john/pathfinder/dist:/home/john/pathfinder/out:/home/john/pathfinder/st/bin:/home/john/bin:/usr/sbin:/sbin:/home/john/pathfinder/st/bin:/usr/local/bin:/usr/bin:/bin:/usr/local/games:/usr/games:.
```