diff --git a/tests/test_errors.py b/tests/test_errors.py
index dc04d0b..4445fad 100644
--- a/tests/test_errors.py
+++ b/tests/test_errors.py
@@ -204,3 +204,8 @@ def test_exception_response_error() -> None:
 def test_exception_unexpected_status_code() -> None:
     with pytest.raises(UnexpectedStatusCodeError):
         Processing(make_response(0, "", {})).process()
+
+
+def test_unkown_scheme(cached_client: Client) -> None:
+    with pytest.raises(ValueError):
+        cached_client.request("ftp://example.com")
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