diff --git a/package.json b/package.json
index b774c64..46ffdb1 100644
--- a/package.json
+++ b/package.json
@@ -8,7 +8,7 @@
     "dependencies": {},
     "devDependencies": {
         "chalk": "^0.5.1",
-        "clean-css": "^2.2.13",
+        "clean-css": "^4.2.1",
         "glob": "^4.0.5",
         "grunt": "~0.4.1",
         "grunt-contrib-clean": "^0.6.0",