diff --git a/clientapi/routing/room_hierarchy.go b/clientapi/routing/room_hierarchy.go
index 639f7b35d..c15559fd0 100644
--- a/clientapi/routing/room_hierarchy.go
+++ b/clientapi/routing/room_hierarchy.go
@@ -34,7 +34,9 @@ type RoomHierarchyPaginationCache struct {
 }
 
 func NewRoomHierarchyPaginationCache() RoomHierarchyPaginationCache {
-	return RoomHierarchyPaginationCache{}
+	return RoomHierarchyPaginationCache{
+		cache: map[string]roomserverAPI.CachedRoomHierarchyWalker{},
+	}
 }
 
 func (c *RoomHierarchyPaginationCache) Get(token string) roomserverAPI.CachedRoomHierarchyWalker {
diff --git a/roomserver/internal/query/query_room_hierarchy.go b/roomserver/internal/query/query_room_hierarchy.go
index a1d9ae2c4..1c12d1222 100644
--- a/roomserver/internal/query/query_room_hierarchy.go
+++ b/roomserver/internal/query/query_room_hierarchy.go
@@ -37,6 +37,7 @@ func (r *Queryer) QueryRoomHierarchy(ctx context.Context, caller types.DeviceOrS
 			parentRoomID: "",
 			depth:        0,
 		}},
+		processed: stringSet{},
 	}
 
 	return &walker