1 files changed, 2 insertions, 2 deletions
diff --git a/synapse/federation/sender/__init__.py b/synapse/federation/sender/__init__.py
index e53b6ac456..4662008bfd 100644
--- a/synapse/federation/sender/__init__.py
+++ b/synapse/federation/sender/__init__.py
@@ -329,10 +329,10 @@ class FederationSender(object):
         room_id = receipt.room_id
 
         # Work out which remote servers should be poked and poke them.
-        domains = await self.state.get_current_hosts_in_room(room_id)
+        domains_set = await self.state.get_current_hosts_in_room(room_id)
         domains = [
             d
-            for d in domains
+            for d in domains_set
             if d != self.server_name
             and self._federation_shard_config.should_handle(self._instance_name, d)
         ]