diff --git a/package.json b/package.json
index 68e3276..52890fc 100644
--- a/package.json
+++ b/package.json
@@ -29,7 +29,7 @@
     "node": ">=4"
   },
   "devDependencies": {
-    "chai": "^3.4.1",
+    "chai": "^4.0.1",
     "codeclimate-test-reporter": "^0.4.0",
     "coveralls": "^2.11.2",
     "istanbul": "^0.4.1",