diff --git a/inbox/mailsync/service.py b/inbox/mailsync/service.py
index 57acefed1..27c5d2070 100644
--- a/inbox/mailsync/service.py
+++ b/inbox/mailsync/service.py
@@ -43,7 +43,7 @@
 SYNC_EVENT_QUEUE_NAME = "sync:event_queue:{}"
 SHARED_SYNC_EVENT_QUEUE_NAME = "sync:shared_event_queue:{}"
 
-SHARED_SYNC_EVENT_QUEUE_ZONE_MAP = {}
+SHARED_SYNC_EVENT_QUEUE_ZONE_MAP: dict[str, EventQueue] = {}
 
 
 def shared_sync_event_queue_for_zone(zone):  # type: ignore[no-untyped-def]  # noqa: ANN201