diff --git a/test/test-utils/test-utils.ts b/test/test-utils/test-utils.ts
index ae7f53865b..1a8792b810 100644
--- a/test/test-utils/test-utils.ts
+++ b/test/test-utils/test-utils.ts
@@ -86,6 +86,7 @@ export function createTestClient(): MatrixClient {
         getUserId: jest.fn().mockReturnValue("@userId:matrix.org"),
         getUser: jest.fn().mockReturnValue({ on: jest.fn() }),
         getDeviceId: jest.fn().mockReturnValue("ABCDEFGHI"),
+        deviceId: "ABCDEFGHI",
         getDevices: jest.fn().mockResolvedValue({ devices: [{ device_id: "ABCDEFGHI" }] }),
         credentials: { userId: "@userId:matrix.org" },