diff --git a/.zsh/configs/tmux.zsh b/.zsh/configs/tmux.zsh
index 61e6ad05..35896603 100644
--- a/.zsh/configs/tmux.zsh
+++ b/.zsh/configs/tmux.zsh
@@ -1,3 +1,7 @@
+_not_inside_tmux() {
+  [[ -z "$TMUX" ]]
+}
+
 ensure_tmux_is_running() {
   if _not_inside_tmux; then
     tat