diff --git a/homeassistant/components/device_tracker/owntracks.py b/homeassistant/components/device_tracker/owntracks.py
index 1e47ed6f83c..3d95e0e0268 100644
--- a/homeassistant/components/device_tracker/owntracks.py
+++ b/homeassistant/components/device_tracker/owntracks.py
@@ -12,7 +12,7 @@ from collections import defaultdict
 import homeassistant.components.mqtt as mqtt
 from homeassistant.const import STATE_HOME
 from homeassistant.util import convert, slugify
-from homeassistant.components import zone
+from homeassistant.components import zone as zone_comp
 
 DEPENDENCIES = ['mqtt']
 
@@ -114,9 +114,9 @@ def setup_scanner(hass, config, see):
 
         def enter_event():
             """Execute enter event."""
-            _zone = hass.states.get("zone.{}".format(location))
+            zone = hass.states.get("zone.{}".format(location))
             with LOCK:
-                if _zone is None and data.get('t') == 'b':
+                if zone is None and data.get('t') == 'b':
                     # Not a HA zone, and a beacon so assume mobile
                     beacons = MOBILE_BEACONS_ACTIVE[dev_id]
                     if location not in beacons:
@@ -128,7 +128,7 @@ def setup_scanner(hass, config, see):
                     if location not in regions:
                         regions.append(location)
                     _LOGGER.info("Enter region %s", location)
-                    _set_gps_from_zone(kwargs, location, _zone)
+                    _set_gps_from_zone(kwargs, location, zone)
 
                 see(**kwargs)
                 see_beacons(dev_id, kwargs)
@@ -143,8 +143,8 @@ def setup_scanner(hass, config, see):
 
                 if new_region:
                     # Exit to previous region
-                    _zone = hass.states.get("zone.{}".format(new_region))
-                    _set_gps_from_zone(kwargs, new_region, _zone)
+                    zone = hass.states.get("zone.{}".format(new_region))
+                    _set_gps_from_zone(kwargs, new_region, zone)
                     _LOGGER.info("Exit to %s", new_region)
                     see(**kwargs)
                     see_beacons(dev_id, kwargs)
@@ -201,7 +201,7 @@ def setup_scanner(hass, config, see):
             lat = wayp['lat']
             lon = wayp['lon']
             rad = wayp['rad']
-            zone.add_zone(hass, name, lat, lon, rad)
+            zone_comp.add_zone(hass, name, lat, lon, rad)
 
     def see_beacons(dev_id, kwargs_param):
         """Set active beacons to the current location."""
@@ -240,12 +240,12 @@ def _parse_see_args(topic, data):
     return dev_id, kwargs
 
 
-def _set_gps_from_zone(kwargs, location, _zone):
+def _set_gps_from_zone(kwargs, location, zone):
     """Set the see parameters from the zone parameters."""
-    if _zone is not None:
+    if zone is not None:
         kwargs['gps'] = (
-            _zone.attributes['latitude'],
-            _zone.attributes['longitude'])
-        kwargs['gps_accuracy'] = _zone.attributes['radius']
+            zone.attributes['latitude'],
+            zone.attributes['longitude'])
+        kwargs['gps_accuracy'] = zone.attributes['radius']
         kwargs['location_name'] = location
     return kwargs
diff --git a/homeassistant/components/zone.py b/homeassistant/components/zone.py
index ee4ff8a48a6..ba63de00823 100644
--- a/homeassistant/components/zone.py
+++ b/homeassistant/components/zone.py
@@ -73,7 +73,7 @@ def in_zone(zone, latitude, longitude, radius=0):
 
 def setup(hass, config):
     """Setup zone."""
-
+    entities = set()
     for key in extract_domain_configs(config, DOMAIN):
         entries = config[key]
         if not isinstance(entries, list):
@@ -92,7 +92,8 @@ def setup(hass, config):
                     'Each zone needs a latitude and longitude.')
                 continue
 
-            zone = Zone(hass, name, latitude, longitude, radius, icon, passive, False)
+            zone = Zone(hass, name, latitude, longitude, radius, icon,
+                        passive, False)
             zone.entity_id = generate_entity_id(ENTITY_ID_FORMAT, name,
                                                 entities)
             zone.update_ha_state()
@@ -100,7 +101,8 @@ def setup(hass, config):
 
     if ENTITY_ID_HOME not in entities:
         zone = Zone(hass, hass.config.location_name, hass.config.latitude,
-                    hass.config.longitude, DEFAULT_RADIUS, ICON_HOME, False, False)
+                    hass.config.longitude, DEFAULT_RADIUS, ICON_HOME,
+                    False, False)
         zone.entity_id = ENTITY_ID_HOME
         zone.update_ha_state()
 
@@ -108,12 +110,13 @@ def setup(hass, config):
 
 # Add a zone to the existing set
 def add_zone(hass, name, latitude, longitude, radius):
+    """Add a zone from other components"""
     _LOGGER.info("Adding new zone %s", name)
     if name not in entities:
         zone = Zone(hass, name, latitude, longitude, radius, ICON_IMPORT,
                     False, True)
         zone.entity_id = generate_entity_id(ENTITY_ID_FORMAT, name,
-                            entities)
+                                            entities)
         zone.update_ha_state()
         entities.add(zone.entity_id)
     else:
@@ -123,7 +126,8 @@ class Zone(Entity):
     """Representation of a Zone."""
 
     # pylint: disable=too-many-arguments, too-many-instance-attributes
-    def __init__(self, hass, name, latitude, longitude, radius, icon, passive, imported):
+    def __init__(self, hass, name, latitude, longitude, radius, icon, passive,
+                 imported):
         """Initialize the zone."""
         self.hass = hass
         self._name = name