diff --git a/package.json b/package.json
index 8848649..924998e 100644
--- a/package.json
+++ b/package.json
@@ -17,7 +17,7 @@
   },
   "homepage": "https://github.com/the-grid/schema#readme",
   "devDependencies": {
-    "chai": "^3.5.0",
+    "chai": "^4.0.0",
     "grunt": "^1.0.1",
     "grunt-coffeelint": "0.0.16",
     "grunt-mocha-test": "^0.13.2",