diff --git a/synapse/config/registration.py b/synapse/config/registration.py
index 87e500c97..f7e03c4cd 100644
--- a/synapse/config/registration.py
+++ b/synapse/config/registration.py
@@ -69,6 +69,7 @@ class RegistrationConfig(Config):
         trusted_third_party_id_servers:
             - matrix.org
             - vector.im
+            - riot.im
         """ % locals()
 
     def add_arguments(self, parser):