diff --git a/src/charm.py b/src/charm.py
index a38bbfd5..3c106aaf 100755
--- a/src/charm.py
+++ b/src/charm.py
@@ -1160,15 +1160,16 @@ def server_cert_sans_dns(self) -> List[str]:
             assert isinstance(target, str), target  # for type checker
             return [target]
 
+        targets: List[str] = [target] if target else []
         # This is an IP address. Try to look up the hostname.
         with contextlib.suppress(OSError, TypeError):
             name, _, _ = socket.gethostbyaddr(target)  # type: ignore
             # Do not return "hostname" like '10-43-8-149.kubernetes.default.svc.cluster.local'
             if is_hostname(name) and not name.endswith(".svc.cluster.local"):
-                return [name]
+                targets.append(cast(str, name))
 
         # If all else fails, we'd rather use the bare IP
-        return [target] if target else []
+        return targets
 
 
 @functools.lru_cache
diff --git a/tests/scenario/test_scheme.py b/tests/scenario/test_scheme.py
deleted file mode 100644
index 94fd1818..00000000
--- a/tests/scenario/test_scheme.py
+++ /dev/null
@@ -1,27 +0,0 @@
-#
-# TODO: implement
-# @pytest.mark.parametrize("scheme", ("http", "https", "h2c"))
-# def test_scheme(traefik_ctx, scheme, traefik_container):
-#     ipa = Relation(
-#         "ingress",
-#         remote_app_data={
-#             "model": "test-model",
-#             "name": "remote",
-#             "port": "42",
-#             "scheme": scheme,
-#         },
-#         remote_units_data={
-#             1: {"host": "foobar.com"}
-#         },
-#     )
-#     state_in = State(
-#         config={"routing_mode": "path", "external_hostname": "foo.com"},
-#         containers=[traefik_container],
-#         relations=[ipa],
-#     )
-#
-#
-#
-# @pytest.mark.parametrize("scheme", ("foo", "bar", "1"))
-# def test_invalid_scheme(scheme):
-#     pass