diff --git a/src/amcrest2mqtt/mixins/helpers.py b/src/amcrest2mqtt/mixins/helpers.py
index 5d64575..4ec9ede 100644
--- a/src/amcrest2mqtt/mixins/helpers.py
+++ b/src/amcrest2mqtt/mixins/helpers.py
@@ -20,11 +20,13 @@ if TYPE_CHECKING:
 
 READY_FILE = os.getenv("READY_FILE", "/tmp/amcrest2mqtt.ready")
 
+
 class ConfigError(ValueError):
     """Raised when the configuration file is invalid."""
 
     pass
 
+
 class HelpersMixin:
     async def build_device_states(self: Amcrest2Mqtt, device_id: str) -> bool:
         if self.is_rebooting(device_id):