diff --git a/util/apop-order-setting.php b/util/apop-order-setting.php
index bbb0d64..f34d694 100644
--- a/util/apop-order-setting.php
+++ b/util/apop-order-setting.php
@@ -192,6 +192,9 @@ if ( ! trait_exists( 'APOP_ORDER_SETTING' ) ) {
 		}
 
 		private static function set_custom_field_orderby( $apop_order_param ): array {
+			if ( ! $apop_order_param ) {
+				return array();
+			}
 			$sort_param = array( 1 => 'ASC', 2 => 'DESC' );
 			$meta_query = null;
 			$orderby    = null;