diff --git a/package.json b/package.json
index efc5003..f02e4a5 100644
--- a/package.json
+++ b/package.json
@@ -42,7 +42,7 @@
     "request": "^2.72.0"
   },
   "devDependencies": {
-    "chai": "^3.4.1",
+    "chai": "^4.0.0",
     "coveralls": "^2.11.6",
     "github-changes": "^1.0.1",
     "istanbul": "^0.4.2",