diff --git a/package.json b/package.json
index 3fecf43..e1268da 100644
--- a/package.json
+++ b/package.json
@@ -12,7 +12,7 @@
     "isomorphic-fetch": "2.2.1"
   },
   "devDependencies": {
-    "chai": "4.2.0",
+    "chai": "6.2.2",
     "koa": "2.5.3",
     "mocha": "2.5.3",
     "supertest": "3.2.0"