diff --git a/package.json b/package.json
index c1f9213..b83e463 100644
--- a/package.json
+++ b/package.json
@@ -51,7 +51,7 @@
     "xtend": "^3.0.0"
   },
   "devDependencies": {
-    "chai": "^1.9.1",
+    "chai": "^4.0.0",
     "express": "^4.12.2",
     "grunt": "^0.4.5",
     "grunt-bg-shell": "^2.3.1",