diff --git a/homeassistant/components/deconz/climate.py b/homeassistant/components/deconz/climate.py
index 0d13f2639da..c5b9571ed34 100644
--- a/homeassistant/components/deconz/climate.py
+++ b/homeassistant/components/deconz/climate.py
@@ -174,7 +174,7 @@ class DeconzThermostat(DeconzDevice[Thermostat], ClimateEntity):
             )
 
     @property
-    def hvac_action(self) -> str | None:
+    def hvac_action(self) -> HVACAction:
         """Return current hvac operation ie. heat, cool.
 
         Preset 'BOOST' is interpreted as 'state_on'.