diff --git a/package.json b/package.json
index 15ecba7..18b7994 100644
--- a/package.json
+++ b/package.json
@@ -62,7 +62,7 @@
     "babel-register": "^6.24.1",
     "babel-runtime": "^6.22.0",
     "bore": "^2.0.1",
-    "chai": "^3.5.0",
+    "chai": "^4.0.2",
     "copy-webpack-plugin": "^4.0.1",
     "coveralls": "^2.12.0",
     "cross-env": "^5.0.0",