diff --git a/package.json b/package.json
index 2e85318..4786828 100644
--- a/package.json
+++ b/package.json
@@ -22,7 +22,7 @@
     "grunt": "~1.0.1",
     "grunt-simple-mocha": "~0.4",
     "grunt-contrib-jshint": "~1.0",
-    "chai": "~3.5",
+    "chai": "~4.0.0",
     "mocha": "~3.0",
     "grunt-npm": "~0.0.2",
     "grunt-bump": "~0.8.0",