Index: wp-includes/rest-api/fields/class-wp-rest-meta-fields.php
===================================================================
--- wp-includes/rest-api/fields/class-wp-rest-meta-fields.php	(revision 41507)
+++ wp-includes/rest-api/fields/class-wp-rest-meta-fields.php	(working copy)
@@ -317,7 +317,7 @@
 	protected function get_registered_fields() {
 		$registered = array();
 
-		foreach ( get_registered_meta_keys( $this->get_meta_type() ) as $name => $args ) {
+		foreach ( get_registered_meta_keys( $this->get_rest_field_type() ) as $name => $args ) {
 			if ( empty( $args['show_in_rest'] ) ) {
 				continue;
 			}