diff --git a/changelog.d/12991.bugfix b/changelog.d/12991.bugfix
new file mode 100644
index 000000000..c6e388d5b
--- /dev/null
+++ b/changelog.d/12991.bugfix
@@ -0,0 +1,2 @@
+Fix a bug where non-standard information was required when requesting the `/hierarchy` API over federation. Introduced 
+in Synapse v1.41.0.
diff --git a/synapse/federation/federation_client.py b/synapse/federation/federation_client.py
index ad475a913..66e630556 100644
--- a/synapse/federation/federation_client.py
+++ b/synapse/federation/federation_client.py
@@ -1642,10 +1642,6 @@ def _validate_hierarchy_event(d: JsonDict) -> None:
     if not isinstance(event_type, str):
         raise ValueError("Invalid event: 'event_type' must be a str")
 
-    room_id = d.get("room_id")
-    if not isinstance(room_id, str):
-        raise ValueError("Invalid event: 'room_id' must be a str")
-
     state_key = d.get("state_key")
     if not isinstance(state_key, str):
         raise ValueError("Invalid event: 'state_key' must be a str")
diff --git a/tests/handlers/test_room_summary.py b/tests/handlers/test_room_summary.py
index 054665569..aa650756e 100644
--- a/tests/handlers/test_room_summary.py
+++ b/tests/handlers/test_room_summary.py
@@ -178,7 +178,7 @@ class SpaceSummaryTestCase(unittest.HomeserverTestCase):
             result_room_ids.append(result_room["room_id"])
             result_children_ids.append(
                 [
-                    (cs["room_id"], cs["state_key"])
+                    (result_room["room_id"], cs["state_key"])
                     for cs in result_room["children_state"]
                 ]
             )