diff --git a/pyoverkiz/enums/ui.py b/pyoverkiz/enums/ui.py
index 933c067c..2aa3b057 100644
--- a/pyoverkiz/enums/ui.py
+++ b/pyoverkiz/enums/ui.py
@@ -1,5 +1,8 @@
+import logging
 from enum import Enum, unique
 
+_LOGGER = logging.getLogger(__name__)
+
 
 @unique
 class UIClass(str, Enum):
@@ -70,6 +73,13 @@ class UIClass(str, Enum):
     WINDOW = "Window"
     WINDOW_HANDLE = "WindowHandle"
 
+    UNKNOWN = "unknown"
+
+    @classmethod
+    def _missing_(cls, value):  # type: ignore
+        _LOGGER.warning(f"Unsupported value {value} has been returned for {cls}")
+        return cls.UNKNOWN
+
 
 @unique
 class UIWidget(str, Enum):
@@ -394,3 +404,10 @@ class UIWidget(str, Enum):
     ZWAVE_TRANSCEIVER = "ZWaveTransceiver"
     ZIGBEE_NETWORK = "ZigbeeNetwork"
     ZIGBEE_STACK = "ZigbeeStack"
+
+    UNKNOWN = "unknown"
+
+    @classmethod
+    def _missing_(cls, value):  # type: ignore
+        _LOGGER.warning(f"Unsupported value {value} has been returned for {cls}")
+        return cls.UNKNOWN
diff --git a/pyoverkiz/models.py b/pyoverkiz/models.py
index e088e907..ada35474 100644
--- a/pyoverkiz/models.py
+++ b/pyoverkiz/models.py
@@ -15,6 +15,8 @@
     GatewaySubType,
     GatewayType,
     ProductType,
+    UIClass,
+    UIWidget,
     UpdateBoxStatus,
 )
 
@@ -151,8 +153,8 @@ class Device:
     controllable_name: str
     definition: Definition
     data_properties: list[dict[str, Any]] | None = None
-    widget: str | None = None
-    ui_class: str | None = None
+    widget: UIWidget
+    ui_class: UIClass
     states: States
     type: ProductType
     place_oid: str
@@ -168,8 +170,8 @@ def __init__(
         controllable_name: str,
         definition: dict[str, Any],
         data_properties: list[dict[str, Any]] | None = None,
-        widget: str | None = None,
-        ui_class: str | None = None,
+        widget: str,
+        ui_class: str,
         states: list[dict[str, Any]] | None = None,
         type: int,
         place_oid: str,
@@ -185,8 +187,8 @@ def __init__(
         self.controllable_name = controllable_name
         self.states = States(states)
         self.data_properties = data_properties
-        self.widget = widget
-        self.ui_class = ui_class
+        self.widget = UIWidget(widget)
+        self.ui_class = UIClass(ui_class)
         self.type = ProductType(type)
         self.place_oid = place_oid