diff --git a/package.json b/package.json
index d64a4c3..3c67a07 100644
--- a/package.json
+++ b/package.json
@@ -39,7 +39,7 @@
     "nyc": "^15.0.0",
     "prettier": "~1.19.1",
     "serve-static": "^1.11.1",
-    "sinon": "^8.0.1",
+    "sinon": "^9.0.0",
     "unexpected": "^11.0.0",
     "unexpected-express": "^12.0.0",
     "unexpected-sinon": "^10.5.0"