diff --git a/modules/ppcp-api-client/src/ApiModule.php b/modules/ppcp-api-client/src/ApiModule.php
index 62e18373f..f12e69668 100644
--- a/modules/ppcp-api-client/src/ApiModule.php
+++ b/modules/ppcp-api-client/src/ApiModule.php
@@ -50,7 +50,7 @@ class ApiModule implements ModuleInterface {
 				foreach ( $data['purchase_units'] as $purchase_unit_index => $purchase_unit ) {
 					foreach ( $purchase_unit['items'] as $item_index => $item ) {
 						$data['purchase_units'][ $purchase_unit_index ]['items'][ $item_index ]['name'] =
-							apply_filters( 'woocommerce_paypal_payments_cart_line_item_name', $item['name'], $item['cart_item_key'] );
+							apply_filters( 'woocommerce_paypal_payments_cart_line_item_name', $item['name'], $item['cart_item_key'] ?? null );
 					}
 				}