diff --git a/package.json b/package.json
index 6943b36..8905892 100644
--- a/package.json
+++ b/package.json
@@ -32,7 +32,7 @@
     "babel-plugin-transform-class-properties": "^6.10.2",
     "babel-preset-es2015": "^6.9.0",
     "babel-register": "^6.9.0",
-    "clean-css": "^3.4.8",
+    "clean-css": "^4.1.11",
     "eslint": "^3.1.0",
     "eslint-config-airbnb-base": "^4.0.2",
     "eslint-plugin-import": "^1.12.0",
diff --git a/yarn.lock b/yarn.lock
index 1dc66d3..792dd48 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -949,13 +949,12 @@ class-utils@^0.3.5:
     isobject "^3.0.0"
     static-extend "^0.1.1"
 
-clean-css@^3.4.8:
-  version "3.4.28"
-  resolved "https://registry.yarnpkg.com/clean-css/-/clean-css-3.4.28.tgz#bf1945e82fc808f55695e6ddeaec01400efd03ff"
-  integrity sha1-vxlF6C/ICPVWlebd6uwBQA79A/8=
+clean-css@^4.1.11:
+  version "4.1.11"
+  resolved "https://registry.yarnpkg.com/clean-css/-/clean-css-4.1.11.tgz#2ecdf145aba38f54740f26cefd0ff3e03e125d6a"
+  integrity sha1-Ls3xRaujj1R0DybO/Q/z4D4SXWo=
   dependencies:
-    commander "2.8.x"
-    source-map "0.4.x"
+    source-map "0.5.x"
 
 cli-cursor@^1.0.1:
   version "1.0.2"
@@ -1025,13 +1024,6 @@ combine-source-map@~0.3.0:
     inline-source-map "~0.3.0"
     source-map "~0.1.31"
 
-commander@2.8.x:
-  version "2.8.1"
-  resolved "https://registry.yarnpkg.com/commander/-/commander-2.8.1.tgz#06be367febfda0c330aa1e2a072d3dc9762425d4"
-  integrity sha1-Br42f+v9oMMwqh4qBy09yXYkJdQ=
-  dependencies:
-    graceful-readlink ">= 1.0.0"
-
 commondir@0.0.1:
   version "0.0.1"
   resolved "https://registry.yarnpkg.com/commondir/-/commondir-0.0.1.tgz#89f00fdcd51b519c578733fec563e6a6da7f5be2"
@@ -1967,11 +1959,6 @@ graceful-fs@~1.2.0:
   resolved "https://registry.yarnpkg.com/graceful-fs/-/graceful-fs-1.2.3.tgz#15a4806a57547cb2d2dbf27f42e89a8c3451b364"
   integrity sha1-FaSAaldUfLLS2/J/QuiajDRRs2Q=
 
-"graceful-readlink@>= 1.0.0":
-  version "1.0.1"
-  resolved "https://registry.yarnpkg.com/graceful-readlink/-/graceful-readlink-1.0.1.tgz#4cafad76bc62f02fa039b2f94e9a3dd3a391a725"
-  integrity sha1-TK+tdrxi8C+gObL5Tpo906ORpyU=
-
 gulp-babel@^6.1.2:
   version "6.1.3"
   resolved "https://registry.yarnpkg.com/gulp-babel/-/gulp-babel-6.1.3.tgz#5aad8acb0db6b7f2f0be19eeee9528f2064df631"
@@ -3865,14 +3852,7 @@ source-map@0.1.34:
   dependencies:
     amdefine ">=0.0.4"
 
-source-map@0.4.x:
-  version "0.4.4"
-  resolved "https://registry.yarnpkg.com/source-map/-/source-map-0.4.4.tgz#eba4f5da9c0dc999de68032d8b4f76173652036b"
-  integrity sha1-66T12pwNyZneaAMti092FzZSA2s=
-  dependencies:
-    amdefine ">=0.0.4"
-
-source-map@^0.5.1, source-map@^0.5.6, source-map@^0.5.7, source-map@~0.5.1:
+source-map@0.5.x, source-map@^0.5.1, source-map@^0.5.6, source-map@^0.5.7, source-map@~0.5.1:
   version "0.5.7"
   resolved "https://registry.yarnpkg.com/source-map/-/source-map-0.5.7.tgz#8a039d2d1021d22d1ea14c80d8ea468ba2ef3fcc"
   integrity sha1-igOdLRAh0i0eoUyA2OpGi6LvP8w=