diff --git a/protected/humhub/modules/user/migrations/m160229_162959_multiusergroups.php b/protected/humhub/modules/user/migrations/m160229_162959_multiusergroups.php
index 9aa0f64220..558bb1592f 100644
--- a/protected/humhub/modules/user/migrations/m160229_162959_multiusergroups.php
+++ b/protected/humhub/modules/user/migrations/m160229_162959_multiusergroups.php
@@ -1,12 +1,15 @@
 <?php
 
 use yii\db\Schema;
+use yii\db\Query;
+use yii\db\Expression;
+use humhub\components\Migration;
 
-class m160229_162959_multiusergroups extends \humhub\components\Migration
+class m160229_162959_multiusergroups extends Migration
 {
     public function up()
     {
-        $this->createTable('group_user', array(
+        $this->createTable('group_user', [
             'id' => 'pk',
             'user_id' => 'int(11) NOT NULL',
             'group_id' => 'int(11) NOT NULL',
@@ -15,53 +18,53 @@ class m160229_162959_multiusergroups extends \humhub\components\Migration
             'created_by' => 'int(11) DEFAULT NULL',
             'updated_at' => 'datetime DEFAULT NULL',
             'updated_by' => 'int(11) DEFAULT NULL',
-        ), '');
-        
-        //Add indexes and foreign keys
+        ], '');
+
+        // Add indexes and foreign keys
         $this->createIndex('idx-group_user', 'group_user', ['user_id', 'group_id'], true);
         $this->addForeignKey('fk-user-group', 'group_user', 'user_id', 'user', 'id', 'CASCADE');
         $this->addForeignKey('fk-group-group', 'group_user', 'group_id', '`group`', 'id', 'CASCADE');
-        
-        //Merge old group user and group admins
+
+        // Merge old group user and group admins
         $this->execute('INSERT INTO group_user (user_id, group_id) SELECT DISTINCT user.id, user.group_id FROM user LEFT JOIN `group` ON user.group_id=group.id WHERE group.id IS NOT NULL');
         $this->execute('UPDATE group_user u SET is_group_admin = :value WHERE EXISTS (Select 1 FROM group_admin a WHERE u.user_id = a.user_id);', [':value' => 1]);
-       
-        //Add group columns
+
+        // Add group columns
         $this->addColumn('group', 'is_admin_group', Schema::TYPE_BOOLEAN. ' NOT NULL DEFAULT 0');
         $this->addColumn('group', 'show_at_registration', Schema::TYPE_BOOLEAN. ' NOT NULL DEFAULT 1');
         $this->addColumn('group', 'show_at_directory', Schema::TYPE_BOOLEAN. ' NOT NULL DEFAULT 1');
-        
-        //Create initial administration group
+
+        // Create initial administration group
         $this->insertSilent('group', [
             'name' => 'Administrator',
             'description' => 'Administrator Group',
             'is_admin_group' => '1',
             'show_at_registration' => '0',
             'show_at_directory' => '0',
-            'created_at' => new \yii\db\Expression('NOW()')
+            'created_at' => new Expression('NOW()')
         ]);
-        
-        //Determine administration group id
-        $adminGroupId = (new \yii\db\Query())
+
+        // Determine administration group id
+        $adminGroupId = (new Query())
                 ->select('id')
                 ->from('group')
                 ->where(['is_admin_group' => '1'])
                 ->scalar();
-        
-        //Load current super_admin user
-        $rows = (new \yii\db\Query())
+
+        // Load current super_admin user
+        $rows = (new Query())
                 ->select("id")
                 ->from('user')
                 ->where(['super_admin' => '1'])
                 ->all();
-        
-        //Insert group_user for administartion groups for all current super_admins
-        foreach($rows as $adminUserRow) {
+
+        // Insert group_user for administration groups for all current super_admins
+        foreach ($rows as $adminUserRow) {
             $this->insertSilent('group_user', ['user_id' => $adminUserRow['id'], 'group_id' => $adminGroupId, 'is_group_admin' => '1']);
         }
-        
+
         //$this->insertSilent('group_permission', ['permission_id' => 'user_admin', 'group_id' => $adminGroupId, 'module_id' => 'user', 'class' => 'humhub\modules\user\permissions']);
-        
+
         $this->dropTable('group_admin');
         $this->dropColumn('user', 'super_admin');
         $this->dropColumn('user', 'group_id');