diff --git a/docs/reference/default-theme/extending.md b/docs/reference/default-theme/extending.md
index 8d6574e075..f1126ea87e 100644
--- a/docs/reference/default-theme/extending.md
+++ b/docs/reference/default-theme/extending.md
@@ -100,7 +100,7 @@ export const childTheme = (options: DefaultThemeOptions): Theme => {
     extends: defaultTheme(options),
 
     // override layouts in child theme's client config file
-    clientConfigFile: path.resolve(__dirname, './client.js'),
+    clientConfigFile: path.resolve(__dirname, './client.ts'),
 
     // override component alias
     alias: {