diff --git a/tests/tls_test.py b/tests/tls_test.py
index bbc89120..ce3da442 100644
--- a/tests/tls_test.py
+++ b/tests/tls_test.py
@@ -141,6 +141,7 @@ def self_signed(*args, **kwargs) -> httpx.AsyncClient:
         ctx = ssl.create_default_context(ssl.Purpose.SERVER_AUTH, cafile=certs["org"]["issuer"])
         if (cert := kwargs.get("cert", None)) is not None:
             ctx.load_cert_chain(certfile=cert[0], keyfile=cert[1])
+            kwargs.pop("cert")
         return httpx.AsyncClient(*args, verify=ctx, **kwargs)
 
     api = await aiopenapi3.OpenAPI.load_async(
@@ -217,6 +218,7 @@ def self_signed_(*args, **kwargs) -> httpx.Client:
         ctx = ssl.create_default_context(ssl.Purpose.SERVER_AUTH, cafile=certs["org"]["issuer"])
         if (cert := kwargs.get("cert", None)) is not None:
             ctx.load_cert_chain(certfile=cert[0], keyfile=cert[1])
+            kwargs.pop("cert")
         return httpx.Client(*args, verify=ctx, **kwargs)
 
     client = await asyncio.to_thread(