diff --git a/module/mr/view/diff.html.php b/module/mr/view/diff.html.php
index ac9a811c7b..a2d835be88 100644
--- a/module/mr/view/diff.html.php
+++ b/module/mr/view/diff.html.php
@@ -55,10 +55,13 @@
             <div class='btn-toolbar'>
               <div class='btn-group'>
                 <div class='btn-group'>
+                  <?php $encoding = str_replace('-', '_', $encoding);?>
                   <?php echo html::commonButton(zget($lang->repo->encodingList, $encoding, $lang->repo->encodingList['utf_8']) . "<span class='caret'></span>", "data-toggle='dropdown'", 'btn dropdown-toggle btn-sm')?>
                   <ul class='dropdown-menu' role='menu'>
                     <?php foreach($lang->repo->encodingList as $key => $val):?>
-                    <li><?php echo html::a('javascript:changeEncoding("'. $key . '")', $val)?></li>
+                    <li <?php echo $key == $encoding ? "class='active'" : '';?>>
+                      <?php echo html::a('javascript:changeEncoding("'. $key . '")', $val)?>
+                    </li>
                     <?php endforeach;?>
                   </ul>
                 </div>