diff --git a/app/lib/constants.rb b/app/lib/constants.rb
index ee75b33b5..e164dd97c 100644
--- a/app/lib/constants.rb
+++ b/app/lib/constants.rb
@@ -32,6 +32,7 @@ module Constants
     "mastodon.cloud",
     "mastodon.gamedev.place",
     "mastodon.host",
+    "mastodon.online",
     "mastodon.sdf.org",
     "mastodon.social",
     "mastodon.technology",