diff --git a/bower.json b/bower.json
index 3000b94..1370afe 100755
--- a/bower.json
+++ b/bower.json
@@ -40,6 +40,7 @@
     "iron-component-page": "^3.0.0",
     "iron-demo-helpers": "^2.0.0",
     "webcomponentsjs": "^1.0.0",
+    "sinonjs": "Polymer/sinon.js#^1.14.1",
     "web-component-tester": "^6.1.5",
     "vaadin-demo-helpers": "vaadin/vaadin-demo-helpers#^3.0.0"
   },