diff --git a/mod/forum/lib.php b/mod/forum/lib.php
index c471cb71898..8aa0b126a17 100644
--- a/mod/forum/lib.php
+++ b/mod/forum/lib.php
@@ -1831,7 +1831,7 @@ function forum_print_discussion_header(&$post, $forum, $group=-1, $datestring=""
                     echo '</a>';
                     echo '<a title="'.$strmarkalldread.'" href="'.$CFG->wwwroot.'/mod/forum/markposts.php?f='.
                          $forum->id.'&amp;d='.$post->discussion.'&amp;mark=read&amp;returnpage=view.php">' .
-                         '<img src="'.$CFG->pixpath.'/t/clear.gif" height="11" width="11" border="0" /></a>';
+                         '<img src="'.$CFG->pixpath.'/t/clear.gif" height="11" width="11" /></a>';
                     echo '</span>';
                 } else {
                     echo '<span class="read">';