diff --git a/lib/prompt-init b/lib/prompt-init
index 8c939f4..d034ebd 100755
--- a/lib/prompt-init
+++ b/lib/prompt-init
@@ -9,12 +9,14 @@ if [[ -a "$OVER_PROMPT_CFG" ]]; then
 fi
 
 # emits garbage on tmux, where it's not really needed anyway
-if [[ ! -n "$TMUX" ]]; then
+if [[ -n "$TMUX" ]]; then
 	function __over_prompt_set_title {
 		if [[ ${TERM} =~ "screen" ]]; then
 			print -Pn "\033k\033${@}\033\134"
 		fi
 	}
+else
+	function __over_prompt_set_title { }
 fi
 
 function __over_prompt_preexec {