diff --git a/homeassistant/components/flume/binary_sensor.py b/homeassistant/components/flume/binary_sensor.py
index 1e0808e7e7d..28f56168d9c 100644
--- a/homeassistant/components/flume/binary_sensor.py
+++ b/homeassistant/components/flume/binary_sensor.py
@@ -40,20 +40,13 @@ BINARY_SENSOR_DESCRIPTION_CONNECTED = BinarySensorEntityDescription(
 )
 
 
-@dataclass(frozen=True)
-class FlumeBinarySensorRequiredKeysMixin:
-    """Mixin for required keys."""
+@dataclass(frozen=True, kw_only=True)
+class FlumeBinarySensorEntityDescription(BinarySensorEntityDescription):
+    """Describes a binary sensor entity."""
 
     event_rule: str
 
 
-@dataclass(frozen=True)
-class FlumeBinarySensorEntityDescription(
-    BinarySensorEntityDescription, FlumeBinarySensorRequiredKeysMixin
-):
-    """Describes a binary sensor entity."""
-
-
 FLUME_BINARY_NOTIFICATION_SENSORS: tuple[FlumeBinarySensorEntityDescription, ...] = (
     FlumeBinarySensorEntityDescription(
         key="leak",