diff --git a/package.json b/package.json
index e4dbc2d..26a181b 100644
--- a/package.json
+++ b/package.json
@@ -68,7 +68,7 @@
     "stylus": "^0.50.0",
     "node-sass": "^2.0.1",
     "less": "^2.4.0",
-    "clean-css": "^3.1.4",
+    "clean-css": "^4.2.1",
     "grunt": "^0.4.5"
   }
 }