diff --git a/package.json b/package.json
index 4de24b0..0fd821c 100644
--- a/package.json
+++ b/package.json
@@ -39,7 +39,7 @@
     "streamifier": "0.1.1"
   },
   "devDependencies": {
-    "chai": "1.6.1",
+    "chai": "4.0.0",
     "chai-fs": "0.1.0",
     "eslint": "3.0.1",
     "eslint-config-airbnb": "9.0.1",