diff --git a/synapse/federation/federation_client.py b/synapse/federation/federation_client.py
index b9c8d8e325..c3e556e7d9 100644
--- a/synapse/federation/federation_client.py
+++ b/synapse/federation/federation_client.py
@@ -307,15 +307,16 @@ class FederationClient(FederationBase):
 
         return signed_pdu
 
-    @defer.inlineCallbacks
-    def get_room_state_ids(self, destination: str, room_id: str, event_id: str):
+    async def get_room_state_ids(
+        self, destination: str, room_id: str, event_id: str
+    ) -> Tuple[List[str], List[str]]:
         """Calls the /state_ids endpoint to fetch the state at a particular point
         in the room, and the auth events for the given event
 
         Returns:
-            Tuple[List[str], List[str]]:  a tuple of (state event_ids, auth event_ids)
+            a tuple of (state event_ids, auth event_ids)
         """
-        result = yield self.transport_layer.get_room_state_ids(
+        result = await self.transport_layer.get_room_state_ids(
             destination, room_id, event_id=event_id
         )