diff --git a/synapse/federation/transport/client.py b/synapse/federation/transport/client.py
index c05d598b70..9204084c67 100644
--- a/synapse/federation/transport/client.py
+++ b/synapse/federation/transport/client.py
@@ -971,7 +971,7 @@ class _StateParser(ByteParser[StateRequestResponse]):
     CONTENT_TYPE = "application/json"
 
     # As with /send_join, /state responses can be huge.
-    MAX_RESPONSE_SIZE = 500 * 1024 * 1024
+    MAX_RESPONSE_SIZE = 600 * 1024 * 1024
 
     def __init__(self, room_version: RoomVersion):
         self._response = StateRequestResponse([], [])