diff --git a/package.json b/package.json
index c771708..152b102 100644
--- a/package.json
+++ b/package.json
@@ -27,7 +27,7 @@
     "yosay": "^1.0.2"
   },
   "devDependencies": {
-    "chai": "^3.0.0",
+    "chai": "^4.0.1",
     "mocha": "*"
   }
 }