diff --git a/powerline/bindings/bash/powerline.sh b/powerline/bindings/bash/powerline.sh
index cc0a22cc..9b4959ba 100644
--- a/powerline/bindings/bash/powerline.sh
+++ b/powerline/bindings/bash/powerline.sh
@@ -8,7 +8,7 @@ fi
 
 _powerline_tmux_setenv() {
 	if [[ -n "$TMUX" ]]; then
-		tmux setenv -g TMUX_"$1"_$(tmux display -p "#D" | tr -d %) "$2"
+		tmux setenv -g TMUX_"$1"_`tmux display -p "#D" | tr -d %` "$2"
 		tmux refresh -S
 	fi
 }