diff --git a/src/Model/LaravelRuleModel.php b/src/Model/LaravelRuleModel.php
index ea7530e..b65f9b3 100644
--- a/src/Model/LaravelRuleModel.php
+++ b/src/Model/LaravelRuleModel.php
@@ -59,9 +59,9 @@ public function __construct(array $data = [], ?string $driver = null)
      *
      * @return mixed
      */
-    protected function config(string $key = null, $default = null)
+    protected function config(?string $key = null, $default = null)
     {
         $driver = $this->driver ?? config('plugin.casbin.webman-permission.permission.default');
         return config('plugin.casbin.webman-permission.permission.' . $driver . '.' . $key, $default);
     }
-}
\ No newline at end of file
+}
diff --git a/src/Permission.php b/src/Permission.php
index 3654f48..dec78b9 100644
--- a/src/Permission.php
+++ b/src/Permission.php
@@ -137,7 +137,7 @@ public static function getDefaultDriver(): mixed
      * @return mixed
      * @author Tinywan(ShaoBo Wan)
      */
-    public static function getConfig(string $name = null, $default = null): mixed
+    public static function getConfig(?string $name = null, $default = null): mixed
     {
         if (!is_null($name)) {
             return config('plugin.casbin.webman-permission.permission.' . $name, $default);