diff --git a/sh/tmux.sh b/sh/tmux.sh
index 85a616f..00ef126 100644
--- a/sh/tmux.sh
+++ b/sh/tmux.sh
@@ -6,7 +6,7 @@
 #= tma
 rwx_tmux_attach() {
 	local server="${1}"
-	if [ "${server}" ]; then
+	if [ -n "${server}" ]; then
 		tmux -L "${server}" attach-session
 	else
 		rwx_tmux_list
@@ -17,7 +17,7 @@ rwx_tmux_attach() {
 #= tmk
 rwx_tmux_kill() {
 	local server="${1}"
-	if [ "${server}" ]; then
+	if [ -n "${server}" ]; then
 		tmux -L "${server}" kill-server 2>"/dev/null"
 	else
 		rwx_tmux_list