diff --git a/misc/quitcd/quitcd.bash_zsh b/misc/quitcd/quitcd.bash_zsh
index f1d93f10..492767a1 100644
--- a/misc/quitcd/quitcd.bash_zsh
+++ b/misc/quitcd/quitcd.bash_zsh
@@ -1,7 +1,7 @@
 n ()
 {
     # Block nesting of nnn in subshells
-    if [ -n $NNNLVL ] && [ "${NNNLVL:-0}" -ge 1 ]; then
+    if [[ "${NNNLVL:-0}" -ge 1 ]]; then
         echo "nnn is already running"
         return
     fi