diff --git a/bower.json b/bower.json
index 5a5af4aaf7..8a1120d472 100644
--- a/bower.json
+++ b/bower.json
@@ -25,7 +25,7 @@
     "webcomponentsjs": "^v1.0.0-rc.5"
   },
   "devDependencies": {
-    "web-component-tester": "^5",
+    "web-component-tester": "^v6.0.0-prerelease.10",
     "test-fixture": "PolymerElements/test-fixture#3.0.0-rc.1"
   },
   "private": true,