diff --git a/package.json b/package.json
index 14f2855..875c0f9 100644
--- a/package.json
+++ b/package.json
@@ -15,7 +15,7 @@
     "babel-preset-stage-2": "^6.5.0",
     "babel-preset-stage-3": "^6.5.0",
     "babel-register": "^6.5.2",
-    "chai": "^3.5.0",
+    "chai": "^4.0.0",
     "compression": "^1.6.1",
     "ejs": "^2.4.1",
     "express": "^4.13.4",