diff --git a/library/include/mobilisis/calculate_price.h b/library/include/mobilisis/calculate_price.h
index 0e5c62a..18fa959 100644
--- a/library/include/mobilisis/calculate_price.h
+++ b/library/include/mobilisis/calculate_price.h
@@ -214,7 +214,10 @@ int CALCULATE_LIBRARY_API get_maximal_parkingprice(Configuration *cfg,
                                                    int paymentOptionIndex=0);
 
 int CALCULATE_LIBRARY_API compute_product_price(Configuration const *cfg,
-                                                PERMIT_TYPE permitType = PERMIT_TYPE::SHORT_TERM_PARKING);
+                                                PERMIT_TYPE permitType = PERMIT_TYPE::SHORT_TERM_PARKING,
+                                                QDateTime const &start = QDateTime::currentDateTime(),
+                                                QDateTime *productStart = nullptr,
+                                                QDateTime *productEnd = nullptr);
 
 CalcState CALCULATE_LIBRARY_API compute_price_for_parking_ticket(       // deprecated
                                             parking_tariff_t *tariff,