diff --git src/wp-includes/rest-api/rest-functions.php src/wp-includes/rest-api/rest-functions.php
index 817368c..df6b879 100644
--- src/wp-includes/rest-api/rest-functions.php
+++ src/wp-includes/rest-api/rest-functions.php
@@ -87,7 +87,7 @@ function register_rest_route( $namespace, $route, $args = array(), $override = f
  *                                              this field. Default is 'null', no schema entry will be returned.
  * }
  */
-function register_api_field( $object_type, $attribute, $args = array() ) {
+function register_rest_field( $object_type, $attribute, $args = array() ) {
 	$defaults = array(
 		'get_callback'    => null,
 		'update_callback' => null,