diff --git a/app/Services/Boot.php b/app/Services/Boot.php
index da6fa77f..1c5ffed1 100644
--- a/app/Services/Boot.php
+++ b/app/Services/Boot.php
@@ -60,7 +60,7 @@ class Boot
             throw new E("检测到 `textures` 文件夹已被删除，请重新运行 <a href='./setup'>安装程序</a>，或者手动放置一个。", -1, true);
         }
 
-        if (Application::getVersion() != @Option::get('version')) {
+        if (Application::getVersion() != Option::get('version', '')) {
             Http::redirect(Http::getBaseUrl().'/setup/update.php');
             exit;
         }
diff --git a/app/Services/Option.php b/app/Services/Option.php
index 77896c78..c694347e 100644
--- a/app/Services/Option.php
+++ b/app/Services/Option.php
@@ -3,41 +3,60 @@
 namespace App\Services;
 
 use Illuminate\Database\Eloquent\Model;
-use App\Exceptions\E;
+use \Exception;
 
 class Option
 {
-    public static function get($key) {
+    public static function get($key, $default_value = null)
+    {
         $option = OptionModel::where('option_name', $key)->first();
-        if (!$option) throw new E('Unexistent option.', 1);
+
+        if (!$option) {
+            if (!is_null($default_value)) {
+                return $default_value;
+            } else {
+                throw new Exception('Unexistent option.', 1);
+            }
+        }
+
         return $option->option_value;
     }
 
-    public static function set($key, $value) {
+    public static function set($key, $value)
+    {
         $option = OptionModel::where('option_name', $key)->first();
-        if (!$option) throw new E('Unexistent option.', 1);
+
+        if (!$option)
+            throw new Exception('Unexistent option.', 1);
+
         $option->option_value = $value;
         return $option->save();
     }
 
-    public static function add($key, $value) {
+    public static function add($key, $value)
+    {
+        if (self::has($key))
+            return true;
+
         $option = new OptionModel;
         $option->option_name = $key;
         $option->option_value = $value;
         $option->save();
     }
 
-    public static function has($key) {
+    public static function has($key)
+    {
         try {
             OptionModel::where('option_name', $key)->firstOrFail();
-        } catch (Illuminate\Database\Eloquent\ModelNotFoundException $e) {
+        } catch (\Illuminate\Database\Eloquent\ModelNotFoundException $e) {
             return false;
         }
         return true;
     }
 
-    public static function delete($key) {
-        OptionModel::where('option_name', $key)->first()->delete();
+    public static function delete($key)
+    {
+        OptionModel::where('option_name', $key)->delete();
     }
 
 }
diff --git a/setup/update.php b/setup/update.php
index 69a88219..059bbf38 100644
--- a/setup/update.php
+++ b/setup/update.php
@@ -24,7 +24,7 @@ if (Config::checkDbConfig($db_config)) {
 }
 
 // If no update is available
-if (App::getVersion() == @Option::get('version')) {
+if (App::getVersion() == Option::get('version', '')) {
     View::show('setup.locked');
     exit;
 }