diff --git a/package.json b/package.json
index 7901113..0a5a1d9 100644
--- a/package.json
+++ b/package.json
@@ -12,7 +12,7 @@
   "devDependencies": {
     "accord": "0.27.0",
     "autoprefixer-stylus": "0.13.0",
-    "chai": "3.5.0",
+    "chai": "4.0.1",
     "coffee-script": "1.12.3",
     "css-parse": "2.0.0",
     "mocha": "3.2.0",