diff --git a/tests/test_routing.py b/tests/test_routing.py
index fb2bfeec..6abdc564 100644
--- a/tests/test_routing.py
+++ b/tests/test_routing.py
@@ -390,6 +390,14 @@ def test_reverse_mount_urls() -> None:
     assert mounted.url_path_for("users:user", subpath="test", username="tom") == "/test/users/tom"
     assert mounted.url_path_for("users", subpath="test", path="/tom") == "/test/users/tom"
 
+    mounted = Router([Mount("/users", ok, name="users")])
+    with pytest.raises(NoMatchFound):
+        mounted.url_path_for("users", path="/a", foo="bar")
+
+    mounted = Router([Mount("/users", ok, name="users")])
+    with pytest.raises(NoMatchFound):
+        mounted.url_path_for("users")
+
 
 def test_mount_at_root(test_client_factory: TestClientFactory) -> None:
     mounted = Router([Mount("/", ok, name="users")])
@@ -479,6 +487,8 @@ def test_host_reverse_urls() -> None:
         mixed_hosts_app.url_path_for("port:homepage").make_absolute_url("https://whatever")
         == "https://port.example.org:3600/"
     )
+    with pytest.raises(NoMatchFound):
+        mixed_hosts_app.url_path_for("api", path="whatever", foo="bar")
 
 
 async def subdomain_app(scope: Scope, receive: Receive, send: Send) -> None: