diff --git a/midealocal/devices/b4/__init__.py b/midealocal/devices/b4/__init__.py
index 35e79d78..dfc4b470 100644
--- a/midealocal/devices/b4/__init__.py
+++ b/midealocal/devices/b4/__init__.py
@@ -1,5 +1,6 @@
 import logging
 import sys
+from typing import Any
 
 from .message import MessageB4Response, MessageQuery
 
@@ -24,7 +25,7 @@ class DeviceAttributes(StrEnum):
 
 
 class MideaB4Device(MideaDevice):
-    _status = {
+    _status: dict[int, str] = {
         0x01: "Standby",
         0x02: "Idle",
         0x03: "Working",
@@ -45,7 +46,7 @@ def __init__(
         model: str,
         subtype: int,
         customize: str,
-    ):
+    ) -> None:
         super().__init__(
             name=name,
             device_id=device_id,
@@ -68,10 +69,10 @@ def __init__(
             },
         )
 
-    def build_query(self):
+    def build_query(self) -> list[MessageQuery]:
         return [MessageQuery(self._protocol_version)]
 
-    def process_message(self, msg):
+    def process_message(self, msg: bytes) -> dict[str, Any]:
         message = MessageB4Response(msg)
         _LOGGER.debug(f"[{self.device_id}] Received: {message}")
         new_status = {}
@@ -90,7 +91,7 @@ def process_message(self, msg):
                 new_status[str(status)] = self._attributes[status]
         return new_status
 
-    def set_attribute(self, attr, value):
+    def set_attribute(self, attr: str, value: Any) -> None:
         pass
 
 
diff --git a/midealocal/devices/b4/message.py b/midealocal/devices/b4/message.py
index 28ec95a7..4d9acc12 100644
--- a/midealocal/devices/b4/message.py
+++ b/midealocal/devices/b4/message.py
@@ -2,7 +2,9 @@
 
 
 class MessageB4Base(MessageRequest):
-    def __init__(self, protocol_version, message_type, body_type):
+    def __init__(
+        self, protocol_version: int, message_type: int, body_type: int
+    ) -> None:
         super().__init__(
             device_type=0xB4,
             protocol_version=protocol_version,
@@ -11,12 +13,12 @@ def __init__(self, protocol_version, message_type, body_type):
         )
 
     @property
-    def _body(self):
+    def _body(self) -> bytearray:
         raise NotImplementedError
 
 
 class MessageQuery(MessageB4Base):
-    def __init__(self, protocol_version):
+    def __init__(self, protocol_version: int) -> None:
         super().__init__(
             protocol_version=protocol_version,
             message_type=MessageType.query,
@@ -24,12 +26,12 @@ def __init__(self, protocol_version):
         )
 
     @property
-    def _body(self):
+    def _body(self) -> bytearray:
         return bytearray([])
 
 
 class B4MessageBody(MessageBody):
-    def __init__(self, body):
+    def __init__(self, body: bytearray) -> None:
         super().__init__(body)
         self.time_remaining = (
             (0 if body[22] == 0xFF else body[22]) * 3600
@@ -47,8 +49,8 @@ def __init__(self, body):
 
 
 class MessageB4Response(MessageResponse):
-    def __init__(self, message):
-        super().__init__(message)
+    def __init__(self, message: bytes) -> None:
+        super().__init__(bytearray(message))
         if self.message_type in [
             MessageType.notify1,
             MessageType.query,