diff --git a/package.json b/package.json
index 753693c8a..6ae1f0b79 100644
--- a/package.json
+++ b/package.json
@@ -74,7 +74,7 @@
     "postcss-nested": "^3.0.0",
     "prettier": "^1.11.1",
     "prop-types": "^15.6.1",
-    "purgecss": "^0.20.1",
+    "purgecss": "^0.21.0",
     "raven-js": "^3.23.3",
     "react-calendar-heatmap": "^1.6.3",
     "react-cosmos": "^4.0.0-beta.0",
diff --git a/yarn.lock b/yarn.lock
index a1fcb7b2e..96dab6c87 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -10495,12 +10495,12 @@ punycode@^1.2.4, punycode@^1.4.1:
   version "1.4.1"
   resolved "https://registry.yarnpkg.com/punycode/-/punycode-1.4.1.tgz#c0d5a63b2718800ad8e1eb0fa5269c84dd41845e"
 
-purgecss@^0.20.1:
-  version "0.20.1"
-  resolved "https://registry.yarnpkg.com/purgecss/-/purgecss-0.20.1.tgz#179f637a0785239e2a67157d191fba9179ea16a4"
+purgecss@^0.21.0:
+  version "0.21.0"
+  resolved "https://registry.yarnpkg.com/purgecss/-/purgecss-0.21.0.tgz#64e62668ef11c9bc03d233843ad7006e1dfe578d"
   dependencies:
     glob "^7.1.2"
-    postcss "^6.0.19"
+    postcss "^6.0.20"
     postcss-selector-parser "^3.1.1"
     yargs "^11.1.0"