diff --git a/webht/third_party/paypal/controllers/index.php b/webht/third_party/paypal/controllers/index.php
index fe5f02ee..3aab75e2 100644
--- a/webht/third_party/paypal/controllers/index.php
+++ b/webht/third_party/paypal/controllers/index.php
@@ -556,7 +556,7 @@ class Index extends CI_Controller {
         $pn_txn_id = $this->input->post('txn_id');
 
         $pn_invoice = $this->input->post('invoice');
-        empty($pn_invoice) ? $pn_invoice = '' : false;
+        empty($pn_invoice) ? $pn_invoice = $this->input->post('transaction_subject') : false;
 
         $pn_custom = $this->input->post('custom');
         empty($pn_custom) ? $pn_custom = '' : false;