diff --git a/view/admin/post/output.html b/view/admin/post/output.html
index 8b0c3f9..b383a82 100644
--- a/view/admin/post/output.html
+++ b/view/admin/post/output.html
@@ -218,6 +218,7 @@
     </div>
 
     <script>
+        $('pre > code:not([class*="language-"])').addClass('language-plaintext');
         $('.code2base64').click(function () {
             $('#post-content').find('pre').each(function (index, elem) {
                 if ($(elem).hasClass('tobase64')) {