diff --git a/package.json b/package.json
index cf57985..8ce59ca 100644
--- a/package.json
+++ b/package.json
@@ -28,7 +28,7 @@
   },
   "homepage": "https://github.com/blakeembrey/map",
   "devDependencies": {
-    "chai": "^3.5.0",
+    "chai": "^4.0.2",
     "istanbul": "^0.4.5",
     "mocha": "^3.3.0"
   }