diff --git a/library/src/calculator_functions.cpp b/library/src/calculator_functions.cpp
index 7018fe8..b3e55d4 100644
--- a/library/src/calculator_functions.cpp
+++ b/library/src/calculator_functions.cpp
@@ -39,7 +39,7 @@ QDateTime Calculator::GetDailyTicketDuration(Configuration* cfg, const QDateTime
 
     int daily_card_price = cfg->PaymentOption.find(payment_option)->second.pop_daily_card_price;
     if(daily_card_price <= 0) {
-        qCritical() << "Calculator::GetDailyTicketDuration(): Daily ticket price zero or less");
+        qCritical() << "Calculator::GetDailyTicketDuration(): Daily ticket price zero or less";
         return QDateTime();
     }
 
@@ -74,12 +74,10 @@ QDateTime Calculator::GetDailyTicketDuration(Configuration* cfg, const QDateTime
     else
     {
         // Get day of week
-        int weekdayId = 0;
-        weekdayId = Utilities::ZellersAlgorithm(inputDateTime.date().day(),inputDateTime.date().month(),inputDateTime.date().year());
+        int const weekdayId = inputDateTime.date().dayOfWeek();
 
         // If no working day found, skip it (recursively call method again)
-        size_t found = 0;
-        found = cfg->WeekDaysWorktime.count(weekdayId);
+        size_t found = cfg->WeekDaysWorktime.count(weekdayId);
 
         // When no workday found, go to next available day
         if(found <=0)