diff --git a/custom_components/versatile_thermostat/underlyings.py b/custom_components/versatile_thermostat/underlyings.py
index 4307c8a..437b15e 100644
--- a/custom_components/versatile_thermostat/underlyings.py
+++ b/custom_components/versatile_thermostat/underlyings.py
@@ -550,14 +550,11 @@ class UnderlyingClimate(UnderlyingEntity):
     def is_device_active(self):
         """If the toggleable device is currently active."""
         if self.is_initialized:
-            return (
-                self._underlying_climate.hvac_mode != HVACMode.OFF
-                and self.hvac_action
-                not in [
-                    HVACAction.IDLE,
-                    HVACAction.OFF,
-                ]
-            )
+            return self.hvac_mode != HVACMode.OFF and self.hvac_action not in [
+                HVACAction.IDLE,
+                HVACAction.OFF,
+                None,
+            ]
         else:
             return None