diff --git a/synapse/rest/client/room.py b/synapse/rest/client/room.py
index e7a6064f5f57..8f66777b5025 100644
--- a/synapse/rest/client/room.py
+++ b/synapse/rest/client/room.py
@@ -603,6 +603,7 @@ def __init__(self, hs: "HomeServer"):
         self.message_handler = hs.get_message_handler()
         self.auth = hs.get_auth()
 
+    @cancellable
     async def on_GET(
         self, request: SynapseRequest, room_id: str
     ) -> Tuple[int, List[JsonDict]]: