diff --git a/package-lock.json b/package-lock.json
index bdf5f7c..efd923a 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -464,12 +464,18 @@
       }
     },
     "clean-css": {
-      "version": "3.4.26",
-      "resolved": "https://registry.npmjs.org/clean-css/-/clean-css-3.4.26.tgz",
-      "integrity": "sha1-VTI7NE/zvO5oSi6sgck9+Ppz3us=",
+      "version": "4.1.11",
+      "resolved": "https://registry.npmjs.org/clean-css/-/clean-css-4.1.11.tgz",
+      "integrity": "sha1-Ls3xRaujj1R0DybO/Q/z4D4SXWo=",
       "requires": {
-        "commander": "2.8.x",
-        "source-map": "0.4.x"
+        "source-map": "0.5.x"
+      },
+      "dependencies": {
+        "source-map": {
+          "version": "0.5.7",
+          "resolved": "https://registry.npmjs.org/source-map/-/source-map-0.5.7.tgz",
+          "integrity": "sha1-igOdLRAh0i0eoUyA2OpGi6LvP8w="
+        }
       }
     },
     "cliui": {
@@ -1420,6 +1426,7 @@
               "version": "1.0.5",
               "resolved": "https://registry.npmjs.org/combined-stream/-/combined-stream-1.0.5.tgz",
               "integrity": "sha1-k4NwpXtKUd6ix3wV1cX9+JUWQAk=",
+              "optional": true,
               "requires": {
                 "delayed-stream": "~1.0.0"
               },
@@ -1427,7 +1434,8 @@
                 "delayed-stream": {
                   "version": "1.0.0",
                   "resolved": "https://registry.npmjs.org/delayed-stream/-/delayed-stream-1.0.0.tgz",
-                  "integrity": "sha1-3zrhmayt+31ECqrgsp4icrJOxhk="
+                  "integrity": "sha1-3zrhmayt+31ECqrgsp4icrJOxhk=",
+                  "optional": true
                 }
               }
             },
@@ -1631,6 +1639,7 @@
                   "version": "2.9.0",
                   "resolved": "https://registry.npmjs.org/boom/-/boom-2.9.0.tgz",
                   "integrity": "sha1-pUt/0v7kd9NRv543FoDL6mfxJxU=",
+                  "optional": true,
                   "requires": {
                     "hoek": "2.x.x"
                   }
@@ -1647,7 +1656,8 @@
                 "hoek": {
                   "version": "2.16.3",
                   "resolved": "https://registry.npmjs.org/hoek/-/hoek-2.16.3.tgz",
-                  "integrity": "sha1-ILt0A9POo5jpHcRxCo/xuCdKJe0="
+                  "integrity": "sha1-ILt0A9POo5jpHcRxCo/xuCdKJe0=",
+                  "optional": true
                 },
                 "sntp": {
                   "version": "1.0.9",
@@ -1701,6 +1711,7 @@
               "version": "2.1.7",
               "resolved": "https://registry.npmjs.org/mime-types/-/mime-types-2.1.7.tgz",
               "integrity": "sha1-/2A5cOPHMe9vf03zyaD0Y6E8J1U=",
+              "optional": true,
               "requires": {
                 "mime-db": "~1.19.0"
               },
@@ -1708,7 +1719,8 @@
                 "mime-db": {
                   "version": "1.19.0",
                   "resolved": "https://registry.npmjs.org/mime-db/-/mime-db-1.19.0.tgz",
-                  "integrity": "sha1-SWoYGYp86CRFNOJbsQK3T7Qg/VY="
+                  "integrity": "sha1-SWoYGYp86CRFNOJbsQK3T7Qg/VY=",
+                  "optional": true
                 }
               }
             },
diff --git a/package.json b/package.json
index 68b57c2..cb8bade 100644
--- a/package.json
+++ b/package.json
@@ -7,7 +7,7 @@
     "async": "^1.4.2",
     "autoprefixer-core": "^5.2.0",
     "babelify": "^6.4.0",
-    "clean-css": "^3.3.1",
+    "clean-css": "^4.1.11",
     "colors": "^1.1.2",
     "debug": "^2.2.0",
     "glob": "^5.0.15",