diff --git a/mod/forum/lib.php b/mod/forum/lib.php
index 6ad9b0a64e7..202b7b252ba 100644
--- a/mod/forum/lib.php
+++ b/mod/forum/lib.php
@@ -1948,7 +1948,7 @@ function forum_print_post(&$post, $courseid, $ownpost=false, $reply=false, $link
         echo '<td class="topic starter">';
     }
 
-    echo '<div class="subject">'.$post->subject.'</div>';
+    echo '<div class="subject">'.format_string($post->subject).'</div>';
 
     echo '<div class="author">';
     $fullname = fullname($post, has_capability('moodle/site:viewfullnames', $modcontext));