diff --git a/src/wp-includes/taxonomy.php b/src/wp-includes/taxonomy.php
index 44307fae60..b1da6f109f 100644
--- a/src/wp-includes/taxonomy.php
+++ b/src/wp-includes/taxonomy.php
@@ -681,6 +681,24 @@ class WP_Tax_Query {
 	 */
 	public $queried_terms = array();
 
+	/**
+	 * Database table that where the metadata's objects are stored (eg $wpdb->users).
+	 *
+	 * @since 4.1.0
+	 * @access public
+	 * @var string
+	 */
+	public $primary_table;
+
+	/**
+	 * Column in primary_table that represents the ID of the object.
+	 *
+	 * @since 4.1.0
+	 * @access public
+	 * @var string
+	 */
+	public $primary_id_column;
+
 	/**
 	 * Constructor.
 	 *