Remove : if alert label is blank

I didn't want to add an alert label to my user alerts so I left the field blank. However, I kept getting the ':' displayed. I updated line 19 in the user-alert.tpl.php file to:

   <div class="user-alert-message"><?php if(strlen($alert_label)){print '<span class="user-label">'.$user_label.':'.'</span>';}?><?php print $body; ?></div>