diff --git a/package.json b/package.json
index 8774a1f..792062b 100644
--- a/package.json
+++ b/package.json
@@ -19,7 +19,7 @@
     "@kazupon/vue-i18n-loader": "^0.2.1",
     "@onsenui/ancss": "^1.0.0",
     "axios": "^0.17.1",
-    "clean-css": "^4.1.9",
+    "clean-css": "^4.1.11",
     "compression-webpack-plugin": "^1.1.3",
     "file-saver": "^1.3.3",
     "jszip": "^3.1.5",
diff --git a/yarn.lock b/yarn.lock
index b5aba5c..1b13bdf 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -1557,9 +1557,9 @@ clap@^1.0.9:
   dependencies:
     chalk "^1.1.3"
 
-clean-css@4.1.x, clean-css@^4.1.9:
-  version "4.1.9"
-  resolved "https://registry.yarnpkg.com/clean-css/-/clean-css-4.1.9.tgz#35cee8ae7687a49b98034f70de00c4edd3826301"
+clean-css@4.1.x, clean-css@^4.1.11:
+  version "4.1.11"
+  resolved "https://registry.yarnpkg.com/clean-css/-/clean-css-4.1.11.tgz#2ecdf145aba38f54740f26cefd0ff3e03e125d6a"
   dependencies:
     source-map "0.5.x"