Index: wp-includes/general-template.php
===================================================================
--- wp-includes/general-template.php	(revision 23588)
+++ wp-includes/general-template.php	(working copy)
@@ -195,7 +195,22 @@
 	else
 		return apply_filters('loginout', $link);
 }
+/**
+ * Returns the user registration URL
+ *
+ * Returns the URL that allows the user to log in to the site
+ *
+ * @since 3.6.0
+ * @uses site_url() To generate the log in URL
+ * @uses apply_filters() calls 'register_url' hook on final url
+ *
+ * @return string
+ */
+function wp_registration_url() {
+	return apply_filters( 'register_url', site_url( 'wp-login.php?action=register', 'login' ) );
+}
 
+
 /**
  * Returns the Log Out URL.
  *
@@ -338,7 +353,7 @@
 
 	if ( ! is_user_logged_in() ) {
 		if ( get_option('users_can_register') )
-			$link = $before . '<a href="' . site_url('wp-login.php?action=register', 'login') . '">' . __('Register') . '</a>' . $after;
+			$link = $before . '<a href="' . esc_url( wp_registration_url() ) . '">' . __('Register') . '</a>' . $after;
 		else
 			$link = '';
 	} else {
Index: wp-login.php
===================================================================
--- wp-login.php	(revision 23588)
+++ wp-login.php	(working copy)
@@ -451,7 +451,7 @@
 <p id="nav">
 <a href="<?php echo esc_url( wp_login_url() ); ?>"><?php _e('Log in') ?></a>
 <?php if ( get_option( 'users_can_register' ) ) : ?>
- | <?php echo apply_filters( 'register', sprintf( '<a href="%s">%s</a>', esc_url( site_url( 'wp-login.php?action=register', 'login' ) ), __( 'Register' ) ) ); ?>
+ | <?php echo apply_filters( 'register', sprintf( '<a href="%s">%s</a>', esc_url( wp_registration_url() ), __( 'Register' ) ) ); ?>
 <?php endif; ?>
 </p>
 
@@ -510,7 +510,7 @@
 <p id="nav">
 <a href="<?php echo esc_url( wp_login_url() ); ?>"><?php _e( 'Log in' ); ?></a>
 <?php if ( get_option( 'users_can_register' ) ) : ?>
- | <?php echo apply_filters( 'register', sprintf( '<a href="%s">%s</a>', esc_url( site_url( 'wp-login.php?action=register', 'login' ) ), __( 'Register' ) ) ); ?>
+ | <?php echo apply_filters( 'register', sprintf( '<a href="%s">%s</a>', esc_url( wp_registration_url() ), __( 'Register' ) ) ); ?>
 <?php endif; ?>
 </p>