diff --git a/package.json b/package.json
index d05526f..913ea66 100644
--- a/package.json
+++ b/package.json
@@ -8,7 +8,7 @@
   ],
   "dependencies": {},
   "devDependencies": {
-    "chai": "^3.5.0",
+    "chai": "^4.2.0",
     "eslint": "^2.7.0",
     "eslint-config-braintree": "^1.0.2",
     "mocha": "^3.2.0"