diff --git a/plugin/dal/lib/DataSource.ts b/plugin/dal/lib/DataSource.ts
index 76fc7137..9ddbb7fa 100644
--- a/plugin/dal/lib/DataSource.ts
+++ b/plugin/dal/lib/DataSource.ts
@@ -21,6 +21,14 @@ import { EggObject, EggObjectLifeCycleContext } from '@eggjs/tegg-runtime';
 import { TableModelManager } from './TableModelManager';
 import { MysqlDataSourceManager } from './MysqlDataSourceManager';
 import { SqlMapManager } from './SqlMapManager';
+import BuiltinModule from 'module';
+
+// Guard against poorly mocked module constructors.
+const Module = module.constructor.length > 1
+  ? module.constructor
+  /* istanbul ignore next */
+  : BuiltinModule;
+const EXTENSION = Object.keys((Module as any)._extensions).find(t => t === '.ts') ? '.ts' : '.js';
 
 @MultiInstanceProto({
   accessLevel: AccessLevel.PUBLIC,
@@ -36,8 +44,7 @@ import { SqlMapManager } from './SqlMapManager';
     } catch {
       return [];
     }
-
-    const daos = dirents.filter(t => t.endsWith('DAO.ts'));
+    const daos = dirents.filter(t => t.endsWith(`DAO${EXTENSION}`));
     // eslint-disable-next-line @typescript-eslint/no-var-requires
     const daoClazzList = daos.map(t => {
       // eslint-disable-next-line @typescript-eslint/no-var-requires