diff --git a/wp-includes/feed.php b/wp-includes/feed.php
index 88f7af44f8..2670ee1fe2 100644
--- a/wp-includes/feed.php
+++ b/wp-includes/feed.php
@@ -683,7 +683,7 @@ function get_feed_build_date( $format ) {
 
 	// Determine the maximum modified time.
 	$datetime = date_create_immutable_from_format(
-		'Y-m-d h:i:s',
+		'Y-m-d H:i:s',
 		max( $modified_times ),
 		new DateTimeZone( 'UTC' )
 	);
diff --git a/wp-includes/version.php b/wp-includes/version.php
index 474d7f79af..cb5b6c229f 100644
--- a/wp-includes/version.php
+++ b/wp-includes/version.php
@@ -13,7 +13,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '5.4-alpha-46756';
+$wp_version = '5.4-alpha-46757';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.