diff --git a/synapse/federation/federation_client.py b/synapse/federation/federation_client.py
index db2c050b3c..14e4b2ae69 100644
--- a/synapse/federation/federation_client.py
+++ b/synapse/federation/federation_client.py
@@ -39,6 +39,7 @@ from synapse.util.caches.expiringcache import ExpiringCache
 from synapse.util.logcontext import make_deferred_yieldable, run_in_background
 from synapse.util.logutils import log_function
 from synapse.util.retryutils import NotRetryingDestination
+from synapse.federation.units import _mangle_pdu
 
 logger = logging.getLogger(__name__)
 
@@ -712,7 +713,7 @@ class FederationClient(FederationBase):
                 destination=destination,
                 room_id=room_id,
                 event_id=event_id,
-                content=pdu.get_pdu_json(time_now),
+                content=_mangle_pdu(pdu.get_pdu_json(time_now)),
             )
         except HttpResponseException as e:
             if e.code == 403:
diff --git a/synapse/handlers/federation.py b/synapse/handlers/federation.py
index 5d8e6c71d8..230a57a872 100644
--- a/synapse/handlers/federation.py
+++ b/synapse/handlers/federation.py
@@ -1420,6 +1420,8 @@ class FederationHandler(BaseHandler):
                 sender, target, event.room_id,
             )
 
+        FrozenEvent.from_event(event)
+        event.unsigned.pop("invite_room_state", None)
         defer.returnValue(event)
 
     @defer.inlineCallbacks