diff --git a/package.json b/package.json
index 3e5fa8c..27951e5 100644
--- a/package.json
+++ b/package.json
@@ -34,7 +34,7 @@
     "postcss": "5.0.12"
   },
   "devDependencies": {
-    "chai": "^3.4.0",
+    "chai": "^4.2.0",
     "eslint": "^2.13.1",
     "eslint-config-hexo": "^1.0.2",
     "istanbul": "^0.4.0",