diff --git a/homeassistant/components/deconz/fan.py b/homeassistant/components/deconz/fan.py
index 3d2e61fdd7b..b8faa95a9b2 100644
--- a/homeassistant/components/deconz/fan.py
+++ b/homeassistant/components/deconz/fan.py
@@ -81,7 +81,7 @@ class DeconzFan(DeconzDevice, FanEntity):
         if self._device.speed == 0:
             return 0
         if self._device.speed not in ORDERED_NAMED_FAN_SPEEDS:
-            return
+            return None
         return ordered_list_item_to_percentage(
             ORDERED_NAMED_FAN_SPEEDS, self._device.speed
         )