diff --git a/tmux/tmux.conf b/tmux/tmux.conf
index 778d0eb..97230a2 100644
--- a/tmux/tmux.conf
+++ b/tmux/tmux.conf
@@ -51,7 +51,7 @@ set -g window-status-format "#[fg=colour235,bg=colour252,bold] #I #W "
 set -g window-status-current-format "#[fg=colour234,bg=colour39]⮀#[fg=black,bg=colour39,noreverse,bold] #I: #W #[fg=colour39,bg=colour234,nobold]⮀"
 
 # Patch for OS X pbpaste and pbcopy under tmux.
-# set-option -g default-command "reattach-to-user-namespace -l zsh"
+set-option -g default-command "which reattach-to-user-namespace > /dev/null && reattach-to-user-namespace -l zsh || zsh"
 
 # Screen like binding
 unbind C-b