diff --git a/client/lib/main.dart b/client/lib/main.dart
index 4c958b7..b92ce01 100644
--- a/client/lib/main.dart
+++ b/client/lib/main.dart
@@ -72,6 +72,9 @@ class _AlreadyRunningApp extends StatelessWidget {
   Widget build(BuildContext context) {
     return MaterialApp(
       debugShowCheckedModeBanner: false,
+      // 必须挂应用主题：DsButton 经 context.tokens 取 AppTokens extension，
+      // 裸 MaterialApp 没有该 extension 会空指针崩溃（弹不出提示框直接闪退）
+      theme: buildTheme('a'),
       home: Builder(
         builder: (context) {
           WidgetsBinding.instance.addPostFrameCallback((_) {