diff --git a/src/database/__tests__/database.test.js b/src/database/__tests__/database.test.js
index 043d11a..1be6ba2 100644
--- a/src/database/__tests__/database.test.js
+++ b/src/database/__tests__/database.test.js
@@ -1,8 +1,9 @@
 import { jest } from '@jest/globals';
 
-// Mock src/database/utils.js (where generateId lives)
+// Mock src/database/utils.js (where generateId and convertObjectIdStringsInFilter live)
 jest.unstable_mockModule('../utils.js', () => ({
   generateId: jest.fn(() => () => 'test-id'),
+  convertObjectIdStringsInFilter: jest.fn((filter) => filter),
 }));
 
 // Mock src/utils.js (where most database.js helpers live)