1 files changed, 1 insertions, 1 deletions
diff --git a/synapse/replication/http/send_event.py b/synapse/replication/http/send_event.py
index c981723c1a..b30e4d5039 100644
--- a/synapse/replication/http/send_event.py
+++ b/synapse/replication/http/send_event.py
@@ -77,7 +77,7 @@ class ReplicationSendEventRestServlet(ReplicationEndpoint):
             extra_users (list(UserID)): Any extra users to notify about event
         """
 
-        serialized_context = yield context.serialize(event, store)
+        serialized_context = yield defer.ensureDeferred(context.serialize(event, store))
 
         payload = {
             "event": event.get_pdu_json(),