diff --git a/includes/core/class-fields.php b/includes/core/class-fields.php
index 9dabd21c..4e9ebccf 100644
--- a/includes/core/class-fields.php
+++ b/includes/core/class-fields.php
@@ -21,6 +21,12 @@ if ( ! class_exists( 'um\core\Fields' ) ) {
 		var $set_mode = '';
 
 
+		/**
+		 * @var int form_id
+		 */
+		public $set_id = null;
+
+
 		/**
 		 * Fields constructor.
 		 */