diff --git a/homeassistant/components/here_travel_time/sensor.py b/homeassistant/components/here_travel_time/sensor.py
index c88aeb8e5a0..f73d3bccaa6 100644
--- a/homeassistant/components/here_travel_time/sensor.py
+++ b/homeassistant/components/here_travel_time/sensor.py
@@ -424,6 +424,9 @@ class HERETravelTimeData:
             if departure is not None:
                 departure = convert_time_to_isodate(departure)
 
+            if departure is None and arrival is None:
+                departure = "now"
+
             _LOGGER.debug(
                 "Requesting route for origin: %s, destination: %s, route_mode: %s, mode: %s, traffic_mode: %s, arrival: %s, departure: %s",
                 origin,
diff --git a/tests/components/here_travel_time/test_sensor.py b/tests/components/here_travel_time/test_sensor.py
index 642b774f1e5..d399f5b67aa 100644
--- a/tests/components/here_travel_time/test_sensor.py
+++ b/tests/components/here_travel_time/test_sensor.py
@@ -80,6 +80,8 @@ def _build_mock_url(origin, destination, modes, api_key, departure=None, arrival
         parameters["arrival"] = arrival
     if departure is not None:
         parameters["departure"] = departure
+    if departure is None and arrival is None:
+        parameters["departure"] = "now"
     url = base_url + urllib.parse.urlencode(parameters)
     print(url)
     return url