diff --git a/src/storefront/views.py b/src/storefront/views.py
index 56da62b..fda99d2 100644
--- a/src/storefront/views.py
+++ b/src/storefront/views.py
@@ -299,8 +299,8 @@ def paypal_order_transaction_capture(request, transaction_id):
             coupon = None
 
         if coupon:
-            form.instance.coupon = coupon
-            coupon.users.add(form.instance.customer)
+            order.coupon = coupon
+            coupon.users.add(order.customer)
         order.save()
         transaction = Transaction.objects.get(order=order)
         transaction.paypal_id = data['purchase_units'][0]['payments']['captures'][0]['id']