diff --git a/package.json b/package.json
index 06daf9c..682e8fa 100644
--- a/package.json
+++ b/package.json
@@ -16,7 +16,7 @@
     "babel-plugin-istanbul": "^4.1.3",
     "babel-preset-es2015": "^6.24.1",
     "babel-register": "^6.24.1",
-    "chai": "^3.5.0",
+    "chai": "^4.1.0",
     "codecov": "^2.2.0",
     "cross-env": "^5.0.0",
     "css-loader": "^0.28.1",