diff --git a/lib/services/notifications/leantime-adapter.ts b/lib/services/notifications/leantime-adapter.ts
index e9b3fafc..176aea80 100644
--- a/lib/services/notifications/leantime-adapter.ts
+++ b/lib/services/notifications/leantime-adapter.ts
@@ -509,7 +509,7 @@ export class LeantimeAdapter implements NotificationAdapter {
           const id = typeof n.id === 'number' ? n.id : parseInt(String(n.id || n.sourceId));
           return isNaN(id) ? null : id;
         })
-        .filter((id): id is number => id !== null);
+        .filter((id: number | null): id is number => id !== null);
       
       console.log(`[LEANTIME_ADAPTER] markAllAsRead - Processing ${notificationIds.length} notifications in batches of ${BATCH_SIZE}`);