diff --git a/wp-includes/theme-compat/comments-popup.php b/wp-includes/theme-compat/comments-popup.php
index eb74834cd3..789742b23e 100644
--- a/wp-includes/theme-compat/comments-popup.php
+++ b/wp-includes/theme-compat/comments-popup.php
@@ -66,7 +66,7 @@ if ( post_password_required($post) ) {  // and it doesn't match the cookie
 <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 &raquo;</a>'), get_edit_user_link(), $user_identity, wp_logout_url(get_permalink())); ?></p>
 <?php else : ?>
diff --git a/wp-includes/theme-compat/comments.php b/wp-includes/theme-compat/comments.php
index 75a85ed46e..a1ae2c66e1 100644
--- a/wp-includes/theme-compat/comments.php
+++ b/wp-includes/theme-compat/comments.php
@@ -65,7 +65,7 @@ _deprecated_file( sprintf( __( 'Theme without %1$s' ), basename(__FILE__) ), '3.
 <p><?php printf(__('You must be <a href="%s">logged in</a> to post a comment.'), wp_login_url( get_permalink() )); ?></p>
 <?php else : ?>
 
-<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 ( is_user_logged_in() ) : ?>