diff --git a/web/template/syzoj/problem.php b/web/template/syzoj/problem.php
index 8737c3f..c892832 100644
--- a/web/template/syzoj/problem.php
+++ b/web/template/syzoj/problem.php
@@ -501,7 +501,7 @@ if ($pr_flag) {
 
     $(document).ready(function () {
       $("#creator").load("problem-ajax.php?pid=<?php echo $id ?>");
-      <?php if (isset($OJ_MARKDOWN) && $OJ_MARKDOWN) { ?>
+      <?php if (isset($OJ_MARKDOWN) && $OJ_MARKDOWN == "marked.js") { ?>
         marked.use({
           // 开启异步渲染
           async: true,
@@ -512,9 +512,9 @@ if ($pr_flag) {
         });
 
         $(".md").each(function () {
-          <?php if ($OJ_MARKDOWN && $OJ_MARKDOWN == "marked.js") { ?>
+          <?php if (isset($OJ_MARKDOWN) && $OJ_MARKDOWN == "marked.js") { ?>
             $(this).html(marked.parse($(this).html()));
-          <?php } else if ($OJ_MARKDOWN && $OJ_MARKDOWN == "markdown-it") { ?>
+          <?php } else if (isset($OJ_MARKDOWN) && $OJ_MARKDOWN == "markdown-it") { ?>
               const md = window.markdownit();
               md.set({
                 html: true,