diff --git a/homeassistant/components/hassio/auth.py b/homeassistant/components/hassio/auth.py
index 951110271d4..4be3ba9956c 100644
--- a/homeassistant/components/hassio/auth.py
+++ b/homeassistant/components/hassio/auth.py
@@ -14,16 +14,16 @@ from homeassistant.components.http import HomeAssistantView
 from homeassistant.components.http.const import KEY_REAL_IP
 from homeassistant.components.http.data_validator import RequestDataValidator
 
-_LOGGER = logging.getLogger(__name__)
+from .const import ATTR_USERNAME, ATTR_PASSWORD, ATTR_ADDON
 
-ATTR_USERNAME = 'username'
-ATTR_PASSWORD = 'password'
+_LOGGER = logging.getLogger(__name__)
 
 
 SCHEMA_API_AUTH = vol.Schema({
     vol.Required(ATTR_USERNAME): cv.string,
     vol.Required(ATTR_PASSWORD): cv.string,
-})
+    vol.Required(ATTR_ADDON): cv.string,
+}, extra=vol.ALLOW_EXTRA)
 
 
 @callback
diff --git a/homeassistant/components/hassio/const.py b/homeassistant/components/hassio/const.py
new file mode 100644
index 00000000000..c539169ebe3
--- /dev/null
+++ b/homeassistant/components/hassio/const.py
@@ -0,0 +1,12 @@
+"""Hass.io const variables."""
+
+ATTR_DISCOVERY = 'discovery'
+ATTR_ADDON = 'addon'
+ATTR_NAME = 'name'
+ATTR_SERVICE = 'service'
+ATTR_CONFIG = 'config'
+ATTR_UUID = 'uuid'
+ATTR_USERNAME = 'username'
+ATTR_PASSWORD = 'password'
+
+X_HASSIO = 'X-HASSIO-KEY'
diff --git a/homeassistant/components/hassio/discovery.py b/homeassistant/components/hassio/discovery.py
index 3c5242607c1..4c7c5a6597f 100644
--- a/homeassistant/components/hassio/discovery.py
+++ b/homeassistant/components/hassio/discovery.py
@@ -10,16 +10,12 @@ from homeassistant.const import EVENT_HOMEASSISTANT_START
 from homeassistant.components.http import HomeAssistantView
 
 from .handler import HassioAPIError
+from .const import (
+    ATTR_DISCOVERY, ATTR_ADDON, ATTR_NAME, ATTR_SERVICE, ATTR_CONFIG,
+    ATTR_UUID)
 
 _LOGGER = logging.getLogger(__name__)
 
-ATTR_DISCOVERY = 'discovery'
-ATTR_ADDON = 'addon'
-ATTR_NAME = 'name'
-ATTR_SERVICE = 'service'
-ATTR_CONFIG = 'config'
-ATTR_UUID = 'uuid'
-
 
 @callback
 def async_setup_discovery(hass, hassio, config):
diff --git a/homeassistant/components/hassio/handler.py b/homeassistant/components/hassio/handler.py
index 7c450b49bcc..91019776eeb 100644
--- a/homeassistant/components/hassio/handler.py
+++ b/homeassistant/components/hassio/handler.py
@@ -16,9 +16,9 @@ from homeassistant.components.http import (
     CONF_SSL_CERTIFICATE)
 from homeassistant.const import CONF_TIME_ZONE, SERVER_PORT
 
-_LOGGER = logging.getLogger(__name__)
+from .const import X_HASSIO
 
-X_HASSIO = 'X-HASSIO-KEY'
+_LOGGER = logging.getLogger(__name__)
 
 
 class HassioAPIError(RuntimeError):
diff --git a/homeassistant/components/hassio/http.py b/homeassistant/components/hassio/http.py
index abd1c16ba8b..c3bd18fa9bb 100644
--- a/homeassistant/components/hassio/http.py
+++ b/homeassistant/components/hassio/http.py
@@ -18,9 +18,10 @@ from aiohttp.web_exceptions import HTTPBadGateway
 from homeassistant.const import CONTENT_TYPE_TEXT_PLAIN
 from homeassistant.components.http import KEY_AUTHENTICATED, HomeAssistantView
 
+from .const import X_HASSIO
+
 _LOGGER = logging.getLogger(__name__)
 
-X_HASSIO = 'X-HASSIO-KEY'
 
 NO_TIMEOUT = re.compile(
     r'^(?:'
diff --git a/tests/components/hassio/test_auth.py b/tests/components/hassio/test_auth.py
index b3a6ae223f9..fdf3230dedc 100644
--- a/tests/components/hassio/test_auth.py
+++ b/tests/components/hassio/test_auth.py
@@ -19,7 +19,8 @@ async def test_login_success(hass, hassio_client):
             '/api/hassio_auth',
             json={
                 "username": "test",
-                "password": "123456"
+                "password": "123456",
+                "addon": "samba",
             },
             headers={
                 HTTP_HEADER_HA_AUTH: API_PASSWORD
@@ -42,7 +43,8 @@ async def test_login_error(hass, hassio_client):
             '/api/hassio_auth',
             json={
                 "username": "test",
-                "password": "123456"
+                "password": "123456",
+                "addon": "samba",
             },
             headers={
                 HTTP_HEADER_HA_AUTH: API_PASSWORD
@@ -83,7 +85,8 @@ async def test_login_no_username(hass, hassio_client):
         resp = await hassio_client.post(
             '/api/hassio_auth',
             json={
-                "password": "123456"
+                "password": "123456",
+                "addon": "samba",
             },
             headers={
                 HTTP_HEADER_HA_AUTH: API_PASSWORD
@@ -93,3 +96,28 @@ async def test_login_no_username(hass, hassio_client):
         # Check we got right response
         assert resp.status == 400
         assert not mock_login.called
+
+
+async def test_login_success_extra(hass, hassio_client):
+    """Test auth with extra data."""
+    await register_auth_provider(hass, {'type': 'homeassistant'})
+
+    with patch('homeassistant.auth.providers.homeassistant.'
+               'HassAuthProvider.async_validate_login',
+               Mock(return_value=mock_coro())) as mock_login:
+        resp = await hassio_client.post(
+            '/api/hassio_auth',
+            json={
+                "username": "test",
+                "password": "123456",
+                "addon": "samba",
+                "path": "/share",
+            },
+            headers={
+                HTTP_HEADER_HA_AUTH: API_PASSWORD
+            }
+        )
+
+        # Check we got right response
+        assert resp.status == 200
+        mock_login.assert_called_with("test", "123456")