diff --git a/samba.sh b/samba.sh
index dda18bb..d306886 100755
--- a/samba.sh
+++ b/samba.sh
@@ -139,6 +139,6 @@ elif [[ $# -ge 1 ]]; then
 elif ps -ef | egrep -v grep | grep -q smbd; then
     echo "Service already running, please restart container to apply changes"
 else
-    [[ $NMBD ]] && ionice -c 3 nmbd -D
+    [[ ${NMBD:-""} ]] && ionice -c 3 nmbd -D
     exec ionice -c 3 smbd -FS
 fi
\ No newline at end of file