Guard is an awesome rubygem which allows livereload among other things. However, when I run guard in tmux it was crashing all my tmux sessions. I guess that is because I am using Tmux 2.2 and Guard tries to use Tmux notifications for notifying about stuff. So, an easy way to fix this problem is to use libnotify for notifications. Just add this line to your Guardfile and you should be good.