diff --git a/package.json b/package.json
index d493ff7..fcd8f2d 100644
--- a/package.json
+++ b/package.json
@@ -8,7 +8,7 @@
     "request": "~2.78.0"
   },
   "devDependencies": {
-    "chai": "~3.5.0",
+    "chai": "~4.0.0",
     "istanbul": "~0.4.5",
     "mocha": "~3.2.0",
     "mocha-lcov-reporter": "~1.2.0",