diff --git a/homeassistant/components/hvv_departures/sensor.py b/homeassistant/components/hvv_departures/sensor.py
index da52fd878d8..d82a15cebe9 100644
--- a/homeassistant/components/hvv_departures/sensor.py
+++ b/homeassistant/components/hvv_departures/sensor.py
@@ -116,7 +116,7 @@ class HVVDepartureSensor(SensorEntity):
             departure_time
             + timedelta(minutes=departure["timeOffset"])
             + timedelta(seconds=delay)
-        ).isoformat()
+        )
 
         self.attr.update(
             {