diff --git a/synapse/handlers/register.py b/synapse/handlers/register.py
index 2b269ab692..2f7bdb0a20 100644
--- a/synapse/handlers/register.py
+++ b/synapse/handlers/register.py
@@ -246,7 +246,8 @@ class RegistrationHandler(BaseHandler):
                         },
                         ratelimit=False,
                     )
-                yield self._join_user_to_room(fake_requester, r)
+                else:
+                    yield self._join_user_to_room(fake_requester, r)
             except Exception as e:
                 logger.error("Failed to join new user to %r: %r", r, e)