diff --git a/homeassistant/components/mfi/sensor.py b/homeassistant/components/mfi/sensor.py
index 38f6d973b9d..84f4abdaead 100644
--- a/homeassistant/components/mfi/sensor.py
+++ b/homeassistant/components/mfi/sensor.py
@@ -133,14 +133,14 @@ class MfiSensor(SensorEntity):
         try:
             tag = self._port.tag
         except ValueError:
-            return "State"
+            return None
 
         if tag == "temperature":
             return UnitOfTemperature.CELSIUS
         if tag == "active_pwr":
             return "Watts"
         if self._port.model == "Input Digital":
-            return "State"
+            return None
         return tag
 
     def update(self) -> None:
diff --git a/tests/components/mfi/test_sensor.py b/tests/components/mfi/test_sensor.py
index ea67ab6f427..f8a043eb8fb 100644
--- a/tests/components/mfi/test_sensor.py
+++ b/tests/components/mfi/test_sensor.py
@@ -148,7 +148,7 @@ async def test_uom_power(port, sensor):
 async def test_uom_digital(port, sensor):
     """Test the UOM digital input."""
     port.model = "Input Digital"
-    assert sensor.unit_of_measurement == "State"
+    assert sensor.unit_of_measurement is None
     assert sensor.device_class is None
 
 
@@ -162,7 +162,7 @@ async def test_uom_unknown(port, sensor):
 async def test_uom_uninitialized(port, sensor):
     """Test that the UOM defaults if not initialized."""
     type(port).tag = mock.PropertyMock(side_effect=ValueError)
-    assert sensor.unit_of_measurement == "State"
+    assert sensor.unit_of_measurement is None
     assert sensor.device_class is None