diff --git a/util/disallowed-cnames.json b/util/disallowed-cnames.json
index b56bfb4ca7..b11b6f798f 100644
--- a/util/disallowed-cnames.json
+++ b/util/disallowed-cnames.json
@@ -1,4 +1,5 @@
 [
     ".cfargotunnel.com",
+    ".trycloudflare.com",
     ".workers.dev"
 ]