diff --git a/library/src/calculate_price.cpp b/library/src/calculate_price.cpp
index 002b091..286715d 100644
--- a/library/src/calculate_price.cpp
+++ b/library/src/calculate_price.cpp
@@ -157,7 +157,7 @@ CalcState CALCULATE_LIBRARY_API compute_price_for_parking_ticket(
 
 
     int const duration = (end_parking_time.toSecsSinceEpoch() -
-                          start_parking_time.toMSecsSinceEpoch()) / 60;
+                          start_parking_time.toSecsSinceEpoch()) / 60;
 
     if (duration < 0) {
         calcState.setDesc(QString("end=%1, start=%2")