<h2><?php _e('Leave a comment'); ?></h2>
<p><?php printf(__('Line and paragraph breaks automatic, e-mail address never displayed, <acronym title="Hypertext Markup Language">HTML</acronym> allowed: <code>%s</code>'), allowed_tags()); ?></p>
-<form action="<?php echo get_option('siteurl'); ?>/wp-comments-post.php" method="post" id="commentform">
+<form action="<?php echo site_url(); ?>/wp-comments-post.php" method="post" id="commentform">
<?php if ( $user_ID ) : ?>
<p><?php printf(__('Logged in as <a href="%1$s">%2$s</a>. <a href="%3$s" title="Log out of this account">Log out »</a>'), get_edit_user_link(), $user_identity, wp_logout_url(get_permalink())); ?></p>
<?php else : ?>