diff --git a/includes/core/class-member-directory-meta.php b/includes/core/class-member-directory-meta.php
index af7ec747..7cbccb40 100644
--- a/includes/core/class-member-directory-meta.php
+++ b/includes/core/class-member-directory-meta.php
@@ -900,7 +900,7 @@ if ( ! class_exists( 'um\core\Member_Directory_Meta' ) ) {
 					$order           = esc_sql( $order );
 					$order           = in_array( strtoupper( $order ), array( 'ASC', 'DESC' ), true ) ? $order : 'ASC';
 					$this->sql_order = " ORDER BY CAST( umm_sort.um_value AS CHAR ) {$order} ";
-				} elseif ( in_array( $sortby, $this->core_search_fields, true ) ) {
+				} elseif ( in_array( $sortby, $this->core_users_fields, true ) ) {
 					$sortby          = esc_sql( $sortby );
 					$order           = esc_sql( $order );
 					$order           = in_array( strtoupper( $order ), array( 'ASC', 'DESC' ), true ) ? $order : 'ASC';
diff --git a/includes/core/class-member-directory.php b/includes/core/class-member-directory.php
index 26a06e6e..8deccf7f 100644
--- a/includes/core/class-member-directory.php
+++ b/includes/core/class-member-directory.php
@@ -58,7 +58,11 @@ if ( ! class_exists( 'um\core\Member_Directory' ) ) {
 
 		var $filter_types = array();
 
-
+		/**
+		 * Fields used for searching from wp_users table.
+		 *
+		 * @var string[]
+		 */
 		var $core_search_fields = array(
 			'user_login',
 			'user_url',
@@ -67,6 +71,19 @@ if ( ! class_exists( 'um\core\Member_Directory' ) ) {
 			'user_nicename',
 		);
 
+		/**
+		 * Fields used for sorting from wp_users table.
+		 *
+		 * @var string[]
+		 */
+		var $core_users_fields = array(
+			'user_login',
+			'user_url',
+			'display_name',
+			'user_email',
+			'user_nicename',
+			'user_registered',
+		);
 
 		/**
 		 * @var