diff --git a/homeassistant/components/pegel_online/sensor.py b/homeassistant/components/pegel_online/sensor.py
index b2b922f3d23..6471b8cbd4b 100644
--- a/homeassistant/components/pegel_online/sensor.py
+++ b/homeassistant/components/pegel_online/sensor.py
@@ -22,20 +22,13 @@ from .coordinator import PegelOnlineDataUpdateCoordinator
 from .entity import PegelOnlineEntity
 
 
-@dataclass(frozen=True)
-class PegelOnlineRequiredKeysMixin:
-    """Mixin for required keys."""
+@dataclass(frozen=True, kw_only=True)
+class PegelOnlineSensorEntityDescription(SensorEntityDescription):
+    """PEGELONLINE sensor entity description."""
 
     measurement_key: str
 
 
-@dataclass(frozen=True)
-class PegelOnlineSensorEntityDescription(
-    SensorEntityDescription, PegelOnlineRequiredKeysMixin
-):
-    """PEGELONLINE sensor entity description."""
-
-
 SENSORS: tuple[PegelOnlineSensorEntityDescription, ...] = (
     PegelOnlineSensorEntityDescription(
         key="air_temperature",