diff --git a/src/wp-includes/functions.php b/src/wp-includes/functions.php
index b3fddfd2b8..c049638e0d 100644
--- a/src/wp-includes/functions.php
+++ b/src/wp-includes/functions.php
@@ -1021,6 +1021,7 @@ function get_status_header_desc( $code ) {
 			428 => 'Precondition Required',
 			429 => 'Too Many Requests',
 			431 => 'Request Header Fields Too Large',
+			451 => 'Unavailable For Legal Reasons',
 
 			500 => 'Internal Server Error',
 			501 => 'Not Implemented',