diff --git a/synapse/handlers/message.py b/synapse/handlers/message.py
index 7b2c33a922..7e40cb6502 100644
--- a/synapse/handlers/message.py
+++ b/synapse/handlers/message.py
@@ -166,6 +166,9 @@ class MessageHandler(object):
         now = self.clock.time_msec()
         events = yield self._event_serializer.serialize_events(
             room_state.values(), now,
+            # We don't bother bundling aggregations in when asked for state
+            # events, as clients won't use them.
+            bundle_aggregations=False,
         )
         defer.returnValue(events)