diff --git a/网页授权.md b/网页授权.md
index 6c4f930..9a13c19 100644
--- a/网页授权.md
+++ b/网页授权.md
@@ -104,6 +104,7 @@ $auth->authorize($to = null, $scope = 'snsapi_userinfo', $state = 'STATE')
 ```php
 
 // 请一定要自己存储用户的登录信息，不要每次都授权
+session_start();
 if (empty($_SESSION['logged_user'])) {
     $user = $auth->authorize(); // 返回用户 Bag
     $_SESSION['logged_user'] = $user->all();