diff --git a/homeassistant/components/homekit/accessories.py b/homeassistant/components/homekit/accessories.py
index 4adeda2465a..2738fafbfdb 100644
--- a/homeassistant/components/homekit/accessories.py
+++ b/homeassistant/components/homekit/accessories.py
@@ -122,6 +122,8 @@ class HomeAccessory(Accessory):
         """
         battery_level = convert_to_float(
             new_state.attributes.get(ATTR_BATTERY_LEVEL))
+        if battery_level is None:
+            return
         self._char_battery.set_value(battery_level)
         self._char_low_battery.set_value(battery_level < 20)
         _LOGGER.debug('%s: Updated battery level to %d', self.entity_id,
diff --git a/tests/components/homekit/test_accessories.py b/tests/components/homekit/test_accessories.py
index 15ab6d7413e..6f3957827eb 100644
--- a/tests/components/homekit/test_accessories.py
+++ b/tests/components/homekit/test_accessories.py
@@ -100,7 +100,7 @@ async def test_home_accessory(hass, hk_driver):
     assert serv.get_characteristic(CHAR_MODEL).value == 'Test Model'
 
 
-async def test_battery_service(hass, hk_driver):
+async def test_battery_service(hass, hk_driver, caplog):
     """Test battery service."""
     entity_id = 'homekit.accessory'
     hass.states.async_set(entity_id, None, {ATTR_BATTERY_LEVEL: 50})
@@ -124,6 +124,13 @@ async def test_battery_service(hass, hk_driver):
     assert acc._char_low_battery.value == 1
     assert acc._char_charging.value == 2
 
+    hass.states.async_set(entity_id, None, {ATTR_BATTERY_LEVEL: 'error'})
+    await hass.async_block_till_done()
+    assert acc._char_battery.value == 15
+    assert acc._char_low_battery.value == 1
+    assert acc._char_charging.value == 2
+    assert 'ERROR' not in caplog.text
+
     # Test charging
     hass.states.async_set(entity_id, None, {
         ATTR_BATTERY_LEVEL: 10, ATTR_BATTERY_CHARGING: True})