diff --git a/package.json b/package.json
index bb66e4a..36da533 100644
--- a/package.json
+++ b/package.json
@@ -21,7 +21,7 @@
     "hamljs": "^0.6.2"
   },
   "devDependencies": {
-    "chai": "^3.5.0",
+    "chai": "^4.2.0",
     "eslint": "^1.10.3",
     "eslint-config-hexo": "^1.0.2",
     "istanbul": "^0.4.2",