diff --git a/package.json b/package.json
index cc87254..5ae6bc8 100644
--- a/package.json
+++ b/package.json
@@ -31,7 +31,7 @@
     "js-yaml": "^3.6.1"
   },
   "devDependencies": {
-    "chai": "^3.5.0",
+    "chai": "^4.0.0",
     "mocha": "^3.3.0"
   }
 }