1 files changed, 1 insertions, 3 deletions
diff --git a/synapse/storage/databases/main/stream.py b/synapse/storage/databases/main/stream.py
index 2e95518752..7dbe11513b 100644
--- a/synapse/storage/databases/main/stream.py
+++ b/synapse/storage/databases/main/stream.py
@@ -259,14 +259,12 @@ def filter_to_clause(event_filter: Optional[Filter]) -> Tuple[str, List[str]]:
     return " AND ".join(clauses), args
 
 
-class StreamWorkerStore(EventsWorkerStore, SQLBaseStore):
+class StreamWorkerStore(EventsWorkerStore, SQLBaseStore, metaclass=abc.ABCMeta):
     """This is an abstract base class where subclasses must implement
     `get_room_max_stream_ordering` and `get_room_min_stream_ordering`
     which can be called in the initializer.
     """
 
-    __metaclass__ = abc.ABCMeta
-
     def __init__(self, database: DatabasePool, db_conn, hs: "HomeServer"):
         super(StreamWorkerStore, self).__init__(database, db_conn, hs)