diff --git a/message/lib.php b/message/lib.php
index 0d76548cdfc..e0e87566104 100644
--- a/message/lib.php
+++ b/message/lib.php
@@ -1979,6 +1979,8 @@ function message_format_message($message, $format='', $keywords='', $class='othe
         $messagetext = highlight($keywords, $messagetext);
     }
 
+    $messagetext = clean_text($messagetext, FORMAT_HTML);
+
     return '<div class="message '.$class.'"><a name="m'.$message->id.'"></a> <span class="time">'.$time.'</span>: <span class="content">'.$messagetext.'</span></div>';
 }