diff --git a/src/dirigera/devices/controller.py b/src/dirigera/devices/controller.py
index 9519548..a6dc021 100644
--- a/src/dirigera/devices/controller.py
+++ b/src/dirigera/devices/controller.py
@@ -5,7 +5,7 @@
 
 
 class ControllerAttributes(Attributes):
-    is_on: bool
+    is_on: Optional[bool] = None
     battery_percentage: Optional[int] = None
     switch_label: Optional[str] = None