diff --git a/index.js b/index.js
index 666f42c..af0ee3d 100644
--- a/index.js
+++ b/index.js
@@ -40,7 +40,7 @@ module.exports = {
     'no-sequences': 'error',
     'no-unmodified-loop-condition': 'error',
     'no-unused-expressions': 'error',
-    'no-unused-vars': 1,
+    'no-unused-vars': 'error',
     'no-useless-call': 'error',
     'no-useless-escape': 'error',
 
diff --git a/package.json b/package.json
index 7f6215f..51246b7 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@glints/eslint-config",
-  "version": "1.1.0",
+  "version": "1.1.1",
   "description": "ESLint rules for Glints projects.",
   "keywords": [
     "eslint",
diff --git a/react.js b/react.js
index 21a146f..80c2324 100644
--- a/react.js
+++ b/react.js
@@ -12,7 +12,7 @@ module.exports = {
     'react/no-unknown-property': 'warn',
     'react/prefer-es6-class': 'warn',
     'react/prefer-stateless-function': 'warn',
-    'react/prop-types': 'warn',
+    'react/prop-types': 'error',
     'react/react-in-jsx-scope': 2,
     'react/require-render-return': 'error',
     'react/self-closing-comp': 'warn',