diff --git a/homeassistant/components/sensor/simulated.py b/homeassistant/components/sensor/simulated.py
index 9dac0b48bc2c3a8eb1923a8b851d38048a617aab..9f114cf2c56a33d5be1018340eff2369b6a7f172 100644
--- a/homeassistant/components/sensor/simulated.py
+++ b/homeassistant/components/sensor/simulated.py
@@ -100,7 +100,7 @@ class SimulatedSensor(Entity):
         else:
             periodic = amp * (math.sin((2*math.pi*time_delta/period) + phase))
         noise = self._random.gauss(mu=0, sigma=fwhm)
-        return mean + periodic + noise
+        return round(mean + periodic + noise, 3)
 
     async def async_update(self):
         """Update the sensor."""
diff --git a/tests/components/sensor/test_simulated.py b/tests/components/sensor/test_simulated.py
index 3bfccc629fdd526cc70b2a32157f279097e4409d..d226c79cff507a6013c345f713e7a35c8a28dabf 100644
--- a/tests/components/sensor/test_simulated.py
+++ b/tests/components/sensor/test_simulated.py
@@ -1,13 +1,14 @@
 """The tests for the simulated sensor."""
 import unittest
 
+from tests.common import get_test_home_assistant
+
 from homeassistant.components.sensor.simulated import (
-    CONF_UNIT, CONF_AMP, CONF_MEAN, CONF_PERIOD, CONF_PHASE, CONF_FWHM,
-    CONF_SEED, DEFAULT_NAME, DEFAULT_AMP, DEFAULT_MEAN,
-    DEFAULT_PHASE, DEFAULT_FWHM, DEFAULT_SEED)
+    CONF_AMP, CONF_FWHM, CONF_MEAN, CONF_PERIOD, CONF_PHASE, CONF_SEED,
+    CONF_UNIT, DEFAULT_AMP, DEFAULT_FWHM, DEFAULT_MEAN, DEFAULT_NAME,
+    DEFAULT_PHASE, DEFAULT_SEED)
 from homeassistant.const import CONF_FRIENDLY_NAME
 from homeassistant.setup import setup_component
-from tests.common import get_test_home_assistant
 
 
 class TestSimulatedSensor(unittest.TestCase):
@@ -27,24 +28,17 @@ class TestSimulatedSensor(unittest.TestCase):
             'sensor': {
                 'platform': 'simulated'}
         }
-        self.assertTrue(
-            setup_component(self.hass, 'sensor', config))
+        self.assertTrue(setup_component(self.hass, 'sensor', config))
         self.hass.block_till_done()
+
         assert len(self.hass.states.entity_ids()) == 1
         state = self.hass.states.get('sensor.simulated')
-        assert state.attributes.get(
-            CONF_FRIENDLY_NAME) == DEFAULT_NAME
-        assert state.attributes.get(
-            CONF_AMP) == DEFAULT_AMP
-        assert state.attributes.get(
-            CONF_UNIT) is None
-        assert state.attributes.get(
-            CONF_MEAN) == DEFAULT_MEAN
-        assert state.attributes.get(
-            CONF_PERIOD) == 60.0
-        assert state.attributes.get(
-            CONF_PHASE) == DEFAULT_PHASE
-        assert state.attributes.get(
-            CONF_FWHM) == DEFAULT_FWHM
-        assert state.attributes.get(
-            CONF_SEED) == DEFAULT_SEED
+
+        assert state.attributes.get(CONF_FRIENDLY_NAME) == DEFAULT_NAME
+        assert state.attributes.get(CONF_AMP) == DEFAULT_AMP
+        assert state.attributes.get(CONF_UNIT) is None
+        assert state.attributes.get(CONF_MEAN) == DEFAULT_MEAN
+        assert state.attributes.get(CONF_PERIOD) == 60.0
+        assert state.attributes.get(CONF_PHASE) == DEFAULT_PHASE
+        assert state.attributes.get(CONF_FWHM) == DEFAULT_FWHM
+        assert state.attributes.get(CONF_SEED) == DEFAULT_SEED