diff --git a/package.json b/package.json
index b1907b0..b82e42e 100644
--- a/package.json
+++ b/package.json
@@ -54,7 +54,7 @@
     "prismjs": "^1.6.0"
   },
   "devDependencies": {
-    "chai": "^3.5.0",
+    "chai": "^4.1.1",
     "doctoc": "^1.3.0",
     "husky": "^0.13.2",
     "jest": "^19.0.2",