diff --git a/homeassistant/components/sensor/knx.py b/homeassistant/components/sensor/knx.py
index 1f5c9a76520..3dce95f7688 100644
--- a/homeassistant/components/sensor/knx.py
+++ b/homeassistant/components/sensor/knx.py
@@ -87,18 +87,11 @@ def update_and_define_min_max(config, minimum_default,
 class KNXSensorBaseClass():
     """Sensor Base Class for all KNX Sensors."""
 
-    _unit_of_measurement = None
-
     @property
     def cache(self):
         """We don't want to cache any Sensor Value."""
         return False
 
-    @property
-    def unit_of_measurement(self):
-        """Return the defined Unit of Measurement for the KNX Sensor."""
-        return self._unit_of_measurement
-
 
 class KNXSensorFloatClass(KNXGroupAddress, KNXSensorBaseClass):
     """
@@ -122,6 +115,11 @@ class KNXSensorFloatClass(KNXGroupAddress, KNXSensorBaseClass):
         """Return the Value of the KNX Sensor."""
         return self._value
 
+    @property
+    def unit_of_measurement(self):
+        """Return the defined Unit of Measurement for the KNX Sensor."""
+        return self._unit_of_measurement
+
     def update(self):
         """Update KNX sensor."""
         from knxip.conversion import knx2_to_float