1 files changed, 3 insertions, 5 deletions
diff --git a/synapse/storage/controllers/persist_events.py b/synapse/storage/controllers/persist_events.py
index abd1d149db..6864f93090 100644
--- a/synapse/storage/controllers/persist_events.py
+++ b/synapse/storage/controllers/persist_events.py
@@ -154,12 +154,13 @@ class _UpdateCurrentStateTask:
 
 
 _EventPersistQueueTask = Union[_PersistEventsTask, _UpdateCurrentStateTask]
+_PersistResult = TypeVar("_PersistResult")
 
 
 @attr.s(auto_attribs=True, slots=True)
-class _EventPersistQueueItem:
+class _EventPersistQueueItem(Generic[_PersistResult]):
     task: _EventPersistQueueTask
-    deferred: ObservableDeferred
+    deferred: ObservableDeferred[_PersistResult]
 
     parent_opentracing_span_contexts: List = attr.ib(factory=list)
     """A list of opentracing spans waiting for this batch"""
@@ -168,9 +169,6 @@ class _EventPersistQueueItem:
     """The opentracing span under which the persistence actually happened"""
 
 
-_PersistResult = TypeVar("_PersistResult")
-
-
 class _EventPeristenceQueue(Generic[_PersistResult]):
     """Queues up tasks so that they can be processed with only one concurrent
     transaction per room.