Index: wp-includes/rest-api/fields/class-wp-rest-post-meta-fields.php
===================================================================
--- wp-includes/rest-api/fields/class-wp-rest-post-meta-fields.php	(revision 40049)
+++ wp-includes/rest-api/fields/class-wp-rest-post-meta-fields.php	(working copy)
@@ -46,7 +46,7 @@
 	 * @return string The meta type.
 	 */
 	protected function get_meta_type() {
-		return 'post';
+		return $this->post_type;
 	}
 
 	/**