diff --git a/wp-includes/functions.php b/wp-includes/functions.php
index 9fba7917d6..8ae58299d6 100644
--- a/wp-includes/functions.php
+++ b/wp-includes/functions.php
@@ -107,6 +107,9 @@ function date_i18n( $dateformatstring, $timestamp_with_offset = false, $gmt = fa
 	 */
 	$req_format = $dateformatstring;
 
+	$dateformatstring = preg_replace( "/(?<!\\\\)c/", DATE_W3C, $dateformatstring );
+	$dateformatstring = preg_replace( "/(?<!\\\\)r/", DATE_RFC2822, $dateformatstring );
+
 	if ( ( ! empty( $wp_locale->month ) ) && ( ! empty( $wp_locale->weekday ) ) ) {
 		$datemonth            = $wp_locale->get_month( date( 'm', $i ) );
 		$datemonth_abbrev     = $wp_locale->get_month_abbrev( $datemonth );
diff --git a/wp-includes/version.php b/wp-includes/version.php
index 10e9e01b75..5a222e871e 100644
--- a/wp-includes/version.php
+++ b/wp-includes/version.php
@@ -4,7 +4,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '5.0-alpha-43406';
+$wp_version = '5.0-alpha-43434';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.