diff --git a/web/app/controllers/problem_statement_manage.php b/web/app/controllers/problem_statement_manage.php
index ab2dfa5..b623642 100644
--- a/web/app/controllers/problem_statement_manage.php
+++ b/web/app/controllers/problem_statement_manage.php
@@ -65,7 +65,7 @@ $problem_editor->runAtServer();
 
 $difficulty_form = new UOJForm('difficulty');
 $difficulty_form->addSelect('difficulty', [
-	'options' => array_combine(UOJProblem::$difficulty, UOJProblem::$difficulty),
+	'options' => [-1 => '暂无评定'] + array_combine(UOJProblem::$difficulty, UOJProblem::$difficulty),
 	'default_value' => UOJProblem::info('difficulty'),
 ]);
 $difficulty_form->handle = function () {
@@ -183,4 +183,4 @@ $difficulty_form->runAtServer();
 
 </div>
 
-<?php echoUOJPageFooter() ?>
\ No newline at end of file
+<?php echoUOJPageFooter() ?>