diff --git a/homeassistant/components/homekit/type_locks.py b/homeassistant/components/homekit/type_locks.py
index b08ac5930bd..309f3072768 100644
--- a/homeassistant/components/homekit/type_locks.py
+++ b/homeassistant/components/homekit/type_locks.py
@@ -5,6 +5,7 @@ from pyhap.const import CATEGORY_DOOR_LOCK
 
 from homeassistant.components.lock import (
     ATTR_ENTITY_ID, STATE_LOCKED, STATE_UNLOCKED, STATE_UNKNOWN)
+from homeassistant.const import ATTR_CODE
 
 from . import TYPES
 from .accessories import HomeAccessory
@@ -32,6 +33,7 @@ class Lock(HomeAccessory):
     def __init__(self, *args):
         """Initialize a Lock accessory object."""
         super().__init__(*args, category=CATEGORY_DOOR_LOCK)
+        self._code = self.config.get(ATTR_CODE)
         self.flag_target_state = False
 
         serv_lock_mechanism = self.add_preload_service(SERV_LOCK)
@@ -51,6 +53,8 @@ class Lock(HomeAccessory):
         service = STATE_TO_SERVICE[hass_value]
 
         params = {ATTR_ENTITY_ID: self.entity_id}
+        if self._code:
+            params[ATTR_CODE] = self._code
         self.hass.services.call('lock', service, params)
 
     def update_state(self, new_state):
diff --git a/homeassistant/components/homekit/util.py b/homeassistant/components/homekit/util.py
index 5ddef534202..5d86dbc4612 100644
--- a/homeassistant/components/homekit/util.py
+++ b/homeassistant/components/homekit/util.py
@@ -30,7 +30,7 @@ def validate_entity_config(values):
 
         domain, _ = split_entity_id(entity)
 
-        if domain == 'alarm_control_panel':
+        if domain in ('alarm_control_panel', 'lock'):
             code = config.get(ATTR_CODE)
             params[ATTR_CODE] = cv.string(code) if code else None
 
diff --git a/tests/components/homekit/test_get_accessories.py b/tests/components/homekit/test_get_accessories.py
index a72f50f6c6f..0ffc1ae4767 100644
--- a/tests/components/homekit/test_get_accessories.py
+++ b/tests/components/homekit/test_get_accessories.py
@@ -39,7 +39,7 @@ def test_customize_options(config, name):
 @pytest.mark.parametrize('type_name, entity_id, state, attrs, config', [
     ('Fan', 'fan.test', 'on', {}, {}),
     ('Light', 'light.test', 'on', {}, {}),
-    ('Lock', 'lock.test', 'locked', {}, {}),
+    ('Lock', 'lock.test', 'locked', {}, {ATTR_CODE: '1234'}),
 
     ('Thermostat', 'climate.test', 'auto', {}, {}),
     ('Thermostat', 'climate.test', 'auto',
diff --git a/tests/components/homekit/test_type_locks.py b/tests/components/homekit/test_type_locks.py
index 984d032a1d9..3b8cde47fcb 100644
--- a/tests/components/homekit/test_type_locks.py
+++ b/tests/components/homekit/test_type_locks.py
@@ -1,19 +1,23 @@
 """Test different accessory types: Locks."""
+import pytest
+
 from homeassistant.components.homekit.type_locks import Lock
 from homeassistant.components.lock import DOMAIN
 from homeassistant.const import (
-    ATTR_ENTITY_ID, STATE_UNKNOWN, STATE_UNLOCKED, STATE_LOCKED)
+    ATTR_CODE, ATTR_ENTITY_ID, STATE_UNKNOWN, STATE_UNLOCKED, STATE_LOCKED)
 
 from tests.common import async_mock_service
 
 
 async def test_lock_unlock(hass):
     """Test if accessory and HA are updated accordingly."""
+    code = '1234'
+    config = {ATTR_CODE: code}
     entity_id = 'lock.kitchen_door'
 
     hass.states.async_set(entity_id, None)
     await hass.async_block_till_done()
-    acc = Lock(hass, 'Lock', entity_id, 2, None)
+    acc = Lock(hass, 'Lock', entity_id, 2, config)
     await hass.async_add_job(acc.run)
 
     assert acc.aid == 2
@@ -50,10 +54,32 @@ async def test_lock_unlock(hass):
     await hass.async_block_till_done()
     assert call_lock
     assert call_lock[0].data[ATTR_ENTITY_ID] == entity_id
+    assert call_lock[0].data[ATTR_CODE] == code
     assert acc.char_target_state.value == 1
 
     await hass.async_add_job(acc.char_target_state.client_update_value, 0)
     await hass.async_block_till_done()
     assert call_unlock
     assert call_unlock[0].data[ATTR_ENTITY_ID] == entity_id
+    assert call_unlock[0].data[ATTR_CODE] == code
     assert acc.char_target_state.value == 0
+
+
+@pytest.mark.parametrize('config', [{}, {ATTR_CODE: None}])
+async def test_no_code(hass, config):
+    """Test accessory if lock doesn't require a code."""
+    entity_id = 'lock.kitchen_door'
+
+    hass.states.async_set(entity_id, None)
+    await hass.async_block_till_done()
+    acc = Lock(hass, 'Lock', entity_id, 2, config)
+
+    # Set from HomeKit
+    call_lock = async_mock_service(hass, DOMAIN, 'lock')
+
+    await hass.async_add_job(acc.char_target_state.client_update_value, 1)
+    await hass.async_block_till_done()
+    assert call_lock
+    assert call_lock[0].data[ATTR_ENTITY_ID] == entity_id
+    assert ATTR_CODE not in call_lock[0].data
+    assert acc.char_target_state.value == 1
diff --git a/tests/components/homekit/test_util.py b/tests/components/homekit/test_util.py
index 0b3a5475f7e..f3ce35ee06b 100644
--- a/tests/components/homekit/test_util.py
+++ b/tests/components/homekit/test_util.py
@@ -30,9 +30,16 @@ def test_validate_entity_config():
     assert vec({}) == {}
     assert vec({'demo.test': {CONF_NAME: 'Name'}}) == \
         {'demo.test': {CONF_NAME: 'Name'}}
+
+    assert vec({'alarm_control_panel.demo': {}}) == \
+        {'alarm_control_panel.demo': {ATTR_CODE: None}}
     assert vec({'alarm_control_panel.demo': {ATTR_CODE: '1234'}}) == \
         {'alarm_control_panel.demo': {ATTR_CODE: '1234'}}
 
+    assert vec({'lock.demo': {}}) == {'lock.demo': {ATTR_CODE: None}}
+    assert vec({'lock.demo': {ATTR_CODE: '1234'}}) == \
+        {'lock.demo': {ATTR_CODE: '1234'}}
+
 
 def test_convert_to_float():
     """Test convert_to_float method."""