diff --git a/homeassistant/components/owntracks/__init__.py b/homeassistant/components/owntracks/__init__.py
index 7e65ff3d51d..d30e667f368 100644
--- a/homeassistant/components/owntracks/__init__.py
+++ b/homeassistant/components/owntracks/__init__.py
@@ -14,12 +14,12 @@ from homeassistant.core import callback
 import homeassistant.helpers.config_validation as cv
 from homeassistant.setup import async_when_setup
 
+from .const import DOMAIN
 from .config_flow import CONF_SECRET
 from .messages import async_handle_message
 
 _LOGGER = logging.getLogger(__name__)
 
-DOMAIN = "owntracks"
 CONF_MAX_GPS_ACCURACY = "max_gps_accuracy"
 CONF_WAYPOINT_IMPORT = "waypoints"
 CONF_WAYPOINT_WHITELIST = "waypoint_whitelist"
diff --git a/homeassistant/components/owntracks/config_flow.py b/homeassistant/components/owntracks/config_flow.py
index 343a6d90b52..a59cd869c74 100644
--- a/homeassistant/components/owntracks/config_flow.py
+++ b/homeassistant/components/owntracks/config_flow.py
@@ -3,6 +3,8 @@ from homeassistant import config_entries
 from homeassistant.const import CONF_WEBHOOK_ID
 from homeassistant.auth.util import generate_secret
 
+from .const import DOMAIN  # noqa pylint: disable=unused-import
+
 CONF_SECRET = "secret"
 CONF_CLOUDHOOK = "cloudhook"
 
@@ -17,8 +19,7 @@ def supports_encryption():
         return False
 
 
-@config_entries.HANDLERS.register("owntracks")
-class OwnTracksFlow(config_entries.ConfigFlow):
+class OwnTracksFlow(config_entries.ConfigFlow, domain=DOMAIN):
     """Set up OwnTracks."""
 
     VERSION = 1
@@ -36,14 +37,9 @@ class OwnTracksFlow(config_entries.ConfigFlow):
         secret = generate_secret(16)
 
         if supports_encryption():
-            secret_desc = (
-                "The encryption key is {} "
-                "(on Android under preferences -> advanced)".format(secret)
-            )
+            secret_desc = f"The encryption key is {secret} (on Android under preferences -> advanced)"
         else:
-            secret_desc = (
-                "Encryption is not supported because libsodium is not " "installed."
-            )
+            secret_desc = "Encryption is not supported because nacl is not installed."
 
         return self.async_create_entry(
             title="OwnTracks",
@@ -55,8 +51,7 @@ class OwnTracksFlow(config_entries.ConfigFlow):
             description_placeholders={
                 "secret": secret_desc,
                 "webhook_url": webhook_url,
-                "android_url": "https://play.google.com/store/apps/details?"
-                "id=org.owntracks.android",
+                "android_url": "https://play.google.com/store/apps/details?id=org.owntracks.android",
                 "ios_url": "https://itunes.apple.com/us/app/owntracks/id692424691?mt=8",
                 "docs_url": "https://www.home-assistant.io/integrations/owntracks/",
             },
@@ -64,6 +59,8 @@ class OwnTracksFlow(config_entries.ConfigFlow):
 
     async def async_step_import(self, user_input):
         """Import a config flow from configuration."""
+        if self._async_current_entries():
+            return self.async_abort(reason="one_instance_allowed")
         webhook_id, _webhook_url, cloudhook = await self._get_webhook_id()
         secret = generate_secret(16)
         return self.async_create_entry(
diff --git a/homeassistant/components/owntracks/const.py b/homeassistant/components/owntracks/const.py
new file mode 100644
index 00000000000..c7caa201ca3
--- /dev/null
+++ b/homeassistant/components/owntracks/const.py
@@ -0,0 +1,3 @@
+"""Constants for OwnTracks."""
+
+DOMAIN = "owntracks"
diff --git a/homeassistant/components/owntracks/messages.py b/homeassistant/components/owntracks/messages.py
index 465d2762f74..0cb65c774b5 100644
--- a/homeassistant/components/owntracks/messages.py
+++ b/homeassistant/components/owntracks/messages.py
@@ -107,7 +107,7 @@ def _decrypt_payload(secret, topic, ciphertext):
     try:
         keylen, decrypt = get_cipher()
     except OSError:
-        _LOGGER.warning("Ignoring encrypted payload because libsodium not installed")
+        _LOGGER.warning("Ignoring encrypted payload because nacl not installed")
         return None
 
     if isinstance(secret, dict):
@@ -117,8 +117,7 @@ def _decrypt_payload(secret, topic, ciphertext):
 
     if key is None:
         _LOGGER.warning(
-            "Ignoring encrypted payload because no decryption key known "
-            "for topic %s",
+            "Ignoring encrypted payload because no decryption key known for topic %s",
             topic,
         )
         return None
@@ -134,8 +133,7 @@ def _decrypt_payload(secret, topic, ciphertext):
         return message
     except ValueError:
         _LOGGER.warning(
-            "Ignoring encrypted payload because unable to decrypt using "
-            "key for topic %s",
+            "Ignoring encrypted payload because unable to decrypt using key for topic %s",
             topic,
         )
         return None
diff --git a/tests/components/owntracks/test_config_flow.py b/tests/components/owntracks/test_config_flow.py
index c4e2a54f69a..54e33a1ab61 100644
--- a/tests/components/owntracks/test_config_flow.py
+++ b/tests/components/owntracks/test_config_flow.py
@@ -1,25 +1,135 @@
 """Tests for OwnTracks config flow."""
-from unittest.mock import patch
+from unittest.mock import Mock, patch
+import pytest
 
+from homeassistant import data_entry_flow
+from homeassistant.const import CONF_WEBHOOK_ID
+from homeassistant.components.owntracks import config_flow
+from homeassistant.components.owntracks.config_flow import CONF_CLOUDHOOK, CONF_SECRET
+from homeassistant.components.owntracks.const import DOMAIN
 from homeassistant.setup import async_setup_component
-from tests.common import mock_coro
+
+from tests.common import mock_coro, MockConfigEntry
 
 
-async def test_config_flow_import(hass):
+CONF_WEBHOOK_URL = "webhook_url"
+
+BASE_URL = "http://example.com"
+CLOUDHOOK = False
+SECRET = "secret"
+WEBHOOK_ID = "webhook_id"
+WEBHOOK_URL = f"{BASE_URL}/api/webhook/webhook_id"
+
+
+@pytest.fixture(name="webhook_id")
+def mock_webhook_id():
+    """Mock webhook_id."""
+    with patch(
+        "homeassistant.components.webhook.async_generate_id", return_value=WEBHOOK_ID
+    ):
+        yield
+
+
+@pytest.fixture(name="secret")
+def mock_secret():
+    """Mock secret."""
+    with patch("binascii.hexlify", return_value=str.encode(SECRET)):
+        yield
+
+
+@pytest.fixture(name="not_supports_encryption")
+def mock_not_supports_encryption():
+    """Mock non successful nacl import."""
+    with patch(
+        "homeassistant.components.owntracks.config_flow.supports_encryption",
+        return_value=False,
+    ):
+        yield
+
+
+def init_config_flow(hass):
+    """Init a configuration flow."""
+    hass.config.api = Mock(base_url=BASE_URL)
+    flow = config_flow.OwnTracksFlow()
+    flow.hass = hass
+    return flow
+
+
+async def test_user(hass, webhook_id, secret):
+    """Test user step."""
+    flow = init_config_flow(hass)
+
+    result = await flow.async_step_user()
+    assert result["type"] == data_entry_flow.RESULT_TYPE_FORM
+    assert result["step_id"] == "user"
+
+    result = await flow.async_step_user({})
+    assert result["type"] == data_entry_flow.RESULT_TYPE_CREATE_ENTRY
+    assert result["title"] == "OwnTracks"
+    assert result["data"][CONF_WEBHOOK_ID] == WEBHOOK_ID
+    assert result["data"][CONF_SECRET] == SECRET
+    assert result["data"][CONF_CLOUDHOOK] == CLOUDHOOK
+    assert result["description_placeholders"][CONF_WEBHOOK_URL] == WEBHOOK_URL
+
+
+async def test_import(hass, webhook_id, secret):
+    """Test import step."""
+    flow = init_config_flow(hass)
+
+    result = await flow.async_step_import({})
+    assert result["type"] == data_entry_flow.RESULT_TYPE_CREATE_ENTRY
+    assert result["title"] == "OwnTracks"
+    assert result["data"][CONF_WEBHOOK_ID] == WEBHOOK_ID
+    assert result["data"][CONF_SECRET] == SECRET
+    assert result["data"][CONF_CLOUDHOOK] == CLOUDHOOK
+    assert result["description_placeholders"] is None
+
+
+async def test_import_setup(hass):
     """Test that we automatically create a config flow."""
-    assert not hass.config_entries.async_entries("owntracks")
-    assert await async_setup_component(hass, "owntracks", {"owntracks": {}})
+    assert not hass.config_entries.async_entries(DOMAIN)
+    assert await async_setup_component(hass, DOMAIN, {"owntracks": {}})
     await hass.async_block_till_done()
-    assert hass.config_entries.async_entries("owntracks")
+    assert hass.config_entries.async_entries(DOMAIN)
 
 
-async def test_config_flow_unload(hass):
+async def test_abort_if_already_setup(hass):
+    """Test that we can't add more than one instance."""
+    flow = init_config_flow(hass)
+
+    MockConfigEntry(domain=DOMAIN, data={}).add_to_hass(hass)
+    assert hass.config_entries.async_entries(DOMAIN)
+
+    # Should fail, already setup (import)
+    result = await flow.async_step_import({})
+    assert result["type"] == data_entry_flow.RESULT_TYPE_ABORT
+    assert result["reason"] == "one_instance_allowed"
+
+    # Should fail, already setup (flow)
+    result = await flow.async_step_user({})
+    assert result["type"] == data_entry_flow.RESULT_TYPE_ABORT
+    assert result["reason"] == "one_instance_allowed"
+
+
+async def test_user_not_supports_encryption(hass, not_supports_encryption):
+    """Test user step."""
+    flow = init_config_flow(hass)
+
+    result = await flow.async_step_user({})
+    assert result["type"] == data_entry_flow.RESULT_TYPE_CREATE_ENTRY
+    assert (
+        result["description_placeholders"]["secret"]
+        == "Encryption is not supported because nacl is not installed."
+    )
+
+
+async def test_unload(hass):
     """Test unloading a config flow."""
     with patch(
         "homeassistant.config_entries.ConfigEntries" ".async_forward_entry_setup"
     ) as mock_forward:
         result = await hass.config_entries.flow.async_init(
-            "owntracks", context={"source": "import"}, data={}
+            DOMAIN, context={"source": "import"}, data={}
         )
 
     assert len(mock_forward.mock_calls) == 1
@@ -51,7 +161,7 @@ async def test_with_cloud_sub(hass):
         return_value=mock_coro("https://hooks.nabu.casa/ABCD"),
     ):
         result = await hass.config_entries.flow.async_init(
-            "owntracks", context={"source": "user"}, data={}
+            DOMAIN, context={"source": "user"}, data={}
         )
 
     entry = result["result"]