diff --git a/zsh/.zsh/configs/tmux.zsh b/zsh/.zsh/configs/tmux.zsh
index 61e6ad05..cb3b1e4f 100644
--- a/zsh/.zsh/configs/tmux.zsh
+++ b/zsh/.zsh/configs/tmux.zsh
@@ -4,4 +4,8 @@ ensure_tmux_is_running() {
   fi
 }
 
+_not_inside_tmux() {
+  [[ -z "$TMUX" ]]
+}
+
 ensure_tmux_is_running