diff --git a/aioesphomeapi/client.py b/aioesphomeapi/client.py
index 2ada885..4f22254 100644
--- a/aioesphomeapi/client.py
+++ b/aioesphomeapi/client.py
@@ -461,34 +461,38 @@ class APIClient:
             entities.append(cls.from_pb(msg))
         return entities, services
 
+    def _on_state_msg(
+        self,
+        on_state: Callable[[EntityState], None],
+        image_stream: dict[int, list[bytes]],
+        msg: message.Message,
+    ) -> None:
+        """Handle a state message."""
+        msg_type = type(msg)
+        if cls := SUBSCRIBE_STATES_RESPONSE_TYPES.get(msg_type):
+            on_state(cls.from_pb(msg))
+        elif msg_type is CameraImageResponse:
+            if TYPE_CHECKING:
+                assert isinstance(msg, CameraImageResponse)
+            msg_key = msg.key
+            data_parts: list[bytes] | None = image_stream.get(msg_key)
+            if not data_parts:
+                data_parts = []
+                image_stream[msg_key] = data_parts
+
+            data_parts.append(msg.data)
+            if msg.done:
+                # Return CameraState with the merged data
+                image_data = b"".join(data_parts)
+                del image_stream[msg_key]
+                on_state(CameraState(key=msg.key, data=image_data))  # type: ignore[call-arg]
+
     async def subscribe_states(self, on_state: Callable[[EntityState], None]) -> None:
-        image_stream: dict[int, list[bytes]] = {}
-        response_types = SUBSCRIBE_STATES_RESPONSE_TYPES
-        msg_types = SUBSCRIBE_STATES_MSG_TYPES
-
-        def _on_state_msg(msg: message.Message) -> None:
-            msg_type = type(msg)
-            cls = response_types.get(msg_type)
-            if cls:
-                on_state(cls.from_pb(msg))
-            elif msg_type is CameraImageResponse:
-                if TYPE_CHECKING:
-                    assert isinstance(msg, CameraImageResponse)
-                msg_key = msg.key
-                data_parts: list[bytes] | None = image_stream.get(msg_key)
-                if not data_parts:
-                    data_parts = []
-                    image_stream[msg_key] = data_parts
-
-                data_parts.append(msg.data)
-                if msg.done:
-                    # Return CameraState with the merged data
-                    image_data = b"".join(data_parts)
-                    del image_stream[msg_key]
-                    on_state(CameraState(key=msg.key, data=image_data))  # type: ignore[call-arg]
-
+        """Subscribe to state updates."""
         self._get_connection().send_message_callback_response(
-            SubscribeStatesRequest(), _on_state_msg, msg_types
+            SubscribeStatesRequest(),
+            partial(self._on_state_msg, on_state, {}),
+            SUBSCRIBE_STATES_MSG_TYPES,
         )
 
     async def subscribe_logs(
@@ -506,17 +510,19 @@ class APIClient:
             req, on_log, (SubscribeLogsResponse,)
         )
 
+    def _on_home_assistant_service_response(
+        self,
+        on_service_call: Callable[[HomeassistantServiceCall], None],
+        msg: HomeassistantServiceResponse,
+    ) -> None:
+        on_service_call(HomeassistantServiceCall.from_pb(msg))
+
     async def subscribe_service_calls(
         self, on_service_call: Callable[[HomeassistantServiceCall], None]
     ) -> None:
-        def _on_home_assistant_service_response(
-            msg: HomeassistantServiceResponse,
-        ) -> None:
-            on_service_call(HomeassistantServiceCall.from_pb(msg))
-
         self._get_connection().send_message_callback_response(
             SubscribeHomeassistantServicesRequest(),
-            _on_home_assistant_service_response,
+            partial(self._on_home_assistant_service_response, on_service_call),
             (HomeassistantServiceResponse,),
         )