killbill-memoizeit

diff --git a/payment/src/main/java/org/killbill/billing/payment/api/svcs/DefaultInvoicePaymentInternalApi.java b/payment/src/main/java/org/killbill/billing/payment/api/svcs/DefaultInvoicePaymentInternalApi.java
index bf91b44..682e88b 100644
--- a/payment/src/main/java/org/killbill/billing/payment/api/svcs/DefaultInvoicePaymentInternalApi.java
+++ b/payment/src/main/java/org/killbill/billing/payment/api/svcs/DefaultInvoicePaymentInternalApi.java
@@ -145,6 +145,6 @@ public class DefaultInvoicePaymentInternalApi extends DefaultApiBase implements 
                            exception);
         }
 
-        return paymentTransaction != null ? invoiceInternalApi.getInvoicePaymentByCookieId(paymentTransactionExternalKey, callContext) : null;
+        return paymentTransaction != null ? invoiceInternalApi.getInvoicePaymentByCookieId(paymentTransaction.getExternalKey(), callContext) : null;
     }
 }