diff --git a/homeassistant/core.py b/homeassistant/core.py
index 496bb018fbd..187dfcf1b83 100644
--- a/homeassistant/core.py
+++ b/homeassistant/core.py
@@ -1079,6 +1079,8 @@ class Config(object):
 
     def is_allowed_path(self, path: str) -> bool:
         """Check if the path is valid for access from outside."""
+        assert path is not None
+
         parent = pathlib.Path(path).parent
         try:
             parent = parent.resolve()  # pylint: disable=no-member
diff --git a/tests/test_core.py b/tests/test_core.py
index 1d22d17f996..b7d049cb747 100644
--- a/tests/test_core.py
+++ b/tests/test_core.py
@@ -833,6 +833,9 @@ class TestConfig(unittest.TestCase):
             for path in unvalid:
                 assert not self.config.is_allowed_path(path)
 
+            with self.assertRaises(AssertionError):
+                self.config.is_allowed_path(None)
+
 
 @patch('homeassistant.core.monotonic')
 def test_create_timer(mock_monotonic, loop):