diff --git a/apps/server/src/wallets/wallets.service.spec.ts b/apps/server/src/wallets/wallets.service.spec.ts
index c730c62..adf919f 100644
--- a/apps/server/src/wallets/wallets.service.spec.ts
+++ b/apps/server/src/wallets/wallets.service.spec.ts
@@ -117,3 +117,54 @@ describe('WalletsService financial boundaries', () => {
     expect(dataSource.transaction).not.toHaveBeenCalled();
   });
 });
+
+describe('WalletsService wallet locking', () => {
+  const createQueryManager = () => {
+    const wallet = { id: 1, studentId: 10, balance: 0 };
+    const query = {
+      where: jest.fn(),
+      setLock: jest.fn(),
+      getOne: jest.fn(async () => wallet),
+    };
+    query.where.mockReturnValue(query);
+    query.setLock.mockReturnValue(query);
+    return {
+      wallet,
+      query,
+      manager: {
+        createQueryBuilder: jest.fn(() => query),
+        findOne: jest.fn(),
+      },
+    };
+  };
+
+  it('skips pessimistic locking for SQLite', async () => {
+    const ctx = createQueryManager();
+    const service = new WalletsService(
+      {} as any,
+      {} as any,
+      {} as any,
+      { options: { type: 'better-sqlite3' } } as any,
+    );
+
+    const result = await (service as any).getOrCreateWallet(ctx.manager, 10, true);
+
+    expect(result).toBe(ctx.wallet);
+    expect(ctx.query.setLock).not.toHaveBeenCalled();
+    expect(ctx.query.getOne).toHaveBeenCalled();
+  });
+
+  it('keeps pessimistic write locking for MySQL', async () => {
+    const ctx = createQueryManager();
+    const service = new WalletsService(
+      {} as any,
+      {} as any,
+      {} as any,
+      { options: { type: 'mysql' } } as any,
+    );
+
+    await (service as any).getOrCreateWallet(ctx.manager, 10, true);
+
+    expect(ctx.query.setLock).toHaveBeenCalledWith('pessimistic_write');
+  });
+});
diff --git a/apps/server/src/wallets/wallets.service.ts b/apps/server/src/wallets/wallets.service.ts
index 1078446..270d2de 100644
--- a/apps/server/src/wallets/wallets.service.ts
+++ b/apps/server/src/wallets/wallets.service.ts
@@ -259,10 +259,13 @@ export class WalletsService {
       if (!lock || !manager.createQueryBuilder) {
         return manager.findOne(StudentWallet, { where: { studentId } });
       }
-      return manager.createQueryBuilder(StudentWallet, 'wallet')
-        .where('wallet.studentId = :studentId', { studentId })
-        .setLock('pessimistic_write')
-        .getOne();
+      let query = manager
+        .createQueryBuilder(StudentWallet, 'wallet')
+        .where('wallet.studentId = :studentId', { studentId });
+      if (['mysql', 'mariadb', 'postgres', 'cockroachdb'].includes(this.dataSource.options.type)) {
+        query = query.setLock('pessimistic_write');
+      }
+      return query.getOne();
     };
     let wallet = await find();
     if (!wallet) {