diff --git a/CRM/Financial/BAO/Order.php b/CRM/Financial/BAO/Order.php
index fc2d59e61cd5..48ece1b8c3a1 100644
--- a/CRM/Financial/BAO/Order.php
+++ b/CRM/Financial/BAO/Order.php
@@ -953,7 +953,8 @@ protected function calculateLineItems(): array {
       elseif ($taxRate) {
         $lineItem['tax_amount'] = ($taxRate / 100) * $lineItem['line_total'];
       }
-      if (!empty($lineItem['membership_type_id'])) {
+      $lineItem['membership_type_id'] = $lineItem['membership_type_id'] ?? NULL;
+      if ($lineItem['membership_type_id']) {
         $lineItem['entity_table'] = 'civicrm_membership';
       }
       $lineItem['title'] = $this->getLineItemTitle($lineItem);