diff --git a/homeassistant/components/sensor/__init__.py b/homeassistant/components/sensor/__init__.py
index 73e6f1fa93a..658c840cd65 100644
--- a/homeassistant/components/sensor/__init__.py
+++ b/homeassistant/components/sensor/__init__.py
@@ -291,7 +291,7 @@ class SensorEntity(Entity):
             # Suppress ValueError (Could not convert sensor_value to float)
             with suppress(ValueError):
                 temp = units.temperature(float(value), unit_of_measurement)
-                value = str(round(temp) if prec == 0 else round(temp, prec))
+                value = round(temp) if prec == 0 else round(temp, prec)
 
         return value
 
diff --git a/tests/components/mhz19/test_sensor.py b/tests/components/mhz19/test_sensor.py
index 5fd3c8e9df1..fd494d6c099 100644
--- a/tests/components/mhz19/test_sensor.py
+++ b/tests/components/mhz19/test_sensor.py
@@ -122,4 +122,4 @@ async def test_temperature_sensor_f(mock_function, hass):
         sensor.hass = hass
         sensor.update()
 
-        assert sensor.state == "75"
+        assert sensor.state == 75