diff --git a/package.json b/package.json
index 24de60d..df76fe7 100644
--- a/package.json
+++ b/package.json
@@ -40,7 +40,7 @@
     "amdclean": "~2.7.0",
     "amdefine": "~1.0.0",
     "async": "~2.0.1",
-    "chai": "~3.5.0",
+    "chai": "~4.0.1",
     "codecov": "~1.0.1",
     "extract-zip": "~1.5.0",
     "google-closure-compiler": "=20160517.0.0",