diff --git a/package.json b/package.json
index dc8ee4a..3c7bf58 100644
--- a/package.json
+++ b/package.json
@@ -34,7 +34,7 @@
   },
   "devDependencies": {
     "beautify-proj": "0.0.4",
-    "chai": "^3.4.1",
+    "chai": "^4.0.0",
     "chai-as-promised": "^5.1.0",
     "coveralls": "^2.11.4",
     "istanbul": "^0.4.0",