diff --git a/root/usr/libexec/apps/bookstack/bookstack.sh b/root/usr/libexec/apps/bookstack/bookstack.sh
index f4dda66..94784f8 100644
--- a/root/usr/libexec/apps/bookstack/bookstack.sh
+++ b/root/usr/libexec/apps/bookstack/bookstack.sh
@@ -110,4 +110,11 @@ case ${ACTION} in
   "port")
     get_image
     CONTAINER_NAMES=$(docker ps -a --filter "ancestor=${IMAGE_NAME}" --format '{{.Names}}')
-    docker ps --all -f "name=${CONTAINER_NAMES}" --format '{{.Ports}}' |
+    docker ps --all -f "name=${CONTAINER_NAMES}" --format '{{.Ports}}' | grep -om1 '0.0.0.0:[0-9]*' | sed 's/0.0.0.0://'
+  ;;
+  *)
+    usage
+    exit 1
+  ;;
+esac
+