diff --git a/src/types.ts b/src/types.ts
index a999bea76..9934054e8 100644
--- a/src/types.ts
+++ b/src/types.ts
@@ -1262,6 +1262,7 @@ export type MarkUnreadOptions = {
   connection_id?: string;
   message_id?: string;
   thread_id?: string;
+  message_timestamp?: string | Date;
   user?: UserResponse;
   user_id?: string;
 };