diff --git a/bmm2/js/Gallery-2.25.2/package.json b/bmm2/js/Gallery-2.25.2/package.json
index b3ef639..27f12b9 100644
--- a/bmm2/js/Gallery-2.25.2/package.json
+++ b/bmm2/js/Gallery-2.25.2/package.json
@@ -33,7 +33,7 @@
   },
   "license": "MIT",
   "devDependencies": {
-    "clean-css": "3.4.21",
+    "clean-css": "4.2.1",
     "standard": "8.6.0",
     "uglify-js": "2.7.4"
   },