diff --git a/package.json b/package.json
index ecccac8f..9be729fc 100644
--- a/package.json
+++ b/package.json
@@ -79,7 +79,7 @@
     "babel-plugin-transform-es2015-modules-commonjs": "^6.22.0",
     "babel-preset-es2015": "^6.22.0",
     "babel-preset-stage-3": "^6.22.0",
-    "chai": "^3.5.0",
+    "chai": "^4.0.1",
     "del": "^2.2.1",
     "gulp": "^3.9.1",
     "gulp-babel": "^6.1.2",