diff --git a/mod/forum/lib.php b/mod/forum/lib.php
index c5b5bcca0f5..8602d85bff6 100644
--- a/mod/forum/lib.php
+++ b/mod/forum/lib.php
@@ -3155,7 +3155,7 @@ function forum_print_post($post, $discussion, $forum, &$cm, $course, $ownpost=fa
             return;
         }
         $output .= html_writer::tag('a', '', array('id'=>'p'.$post->id));
-        $output .= html_writer::start_tag('div', array('class'=>'forumpost clearfix '.$forumpostclass));
+        $output .= html_writer::start_tag('div', array('class'=>'forumpost clearfix'));
         $output .= html_writer::start_tag('div', array('class'=>'row header'));
         $output .= html_writer::tag('div', '', array('class'=>'left picture')); // Picture
         if ($post->parent) {