diff --git a/extensions/feishu/src/monitor.test-mocks.ts b/extensions/feishu/src/monitor.test-mocks.ts
index 083088cdd..2c95375d1 100644
--- a/extensions/feishu/src/monitor.test-mocks.ts
+++ b/extensions/feishu/src/monitor.test-mocks.ts
@@ -1,6 +1,6 @@
 import { vi } from "vitest";
 
-export const probeFeishuMock = vi.hoisted(() => vi.fn());
+export const probeFeishuMock: ReturnType<typeof vi.fn> = vi.hoisted(() => vi.fn());
 
 vi.mock("./probe.js", () => ({
   probeFeishu: probeFeishuMock,