diff --git a/library/include/mobilisis/tariff_carryover.h b/library/include/mobilisis/tariff_carryover.h
index 901881e..7f5085c 100644
--- a/library/include/mobilisis/tariff_carryover.h
+++ b/library/include/mobilisis/tariff_carryover.h
@@ -65,13 +65,22 @@ struct ATBTariffCarryOver {
         int minutes = 0;
         QString end = m_range.m_end.toString(Qt::ISODate);
         if (end == "24:00:00") {
-            QDateTime t = dt.addDays(1);
-            t.setTime(QTime(0,0,0));
-            minutes = dt.secsTo(t) / 60;
+            // note: this did not work
+            // QDateTime t(dt.addDays(1));
+            // t.setTime(QTime(0,0,0));
+            // dt: 2024-10-27T00:00:00 EEST, but t: 2024-10-28T00:00:00 EET (!)
+            // so the difference is 1500 instead of 1440
+            // reason: change from summer to winter time
+
+            // compute minutes directly
+            if (dt.time().isValid()) {
+                minutes = 1440 - (dt.time().hour() * 60 + dt.time().minute());
+            }
         } else {
-            QDateTime t(dt);
-            t.setTime(QTime::fromString(end, Qt::ISODate));
-            minutes = dt.secsTo(t) / 60;
+            QTime t(QTime::fromString(end, Qt::ISODate));
+            if (t.isValid() && dt.time().isValid()) {
+                minutes = (t.hour() * 60 + t.minute()) - (dt.time().hour() * 60 + dt.time().minute());
+            }
         }
 
         if (minutes < 0 || minutes > m_range.m_duration) {