diff --git a/src/orb/_utils/_reflection.py b/src/orb/_utils/_reflection.py
index 9a53c7bd..89aa712a 100644
--- a/src/orb/_utils/_reflection.py
+++ b/src/orb/_utils/_reflection.py
@@ -34,7 +34,7 @@ def assert_signatures_in_sync(
 
         if custom_param.annotation != source_param.annotation:
             errors.append(
-                f"types for the `{name}` param are do not match; source={repr(source_param.annotation)} checking={repr(source_param.annotation)}"
+                f"types for the `{name}` param are do not match; source={repr(source_param.annotation)} checking={repr(custom_param.annotation)}"
             )
             continue
 
diff --git a/tests/test_client.py b/tests/test_client.py
index 33fa1df0..8b038c1d 100644
--- a/tests/test_client.py
+++ b/tests/test_client.py
@@ -17,6 +17,7 @@
 from pydantic import ValidationError
 
 from orb import Orb, AsyncOrb, APIResponseValidationError
+from orb._types import Omit
 from orb._models import BaseModel, FinalRequestOptions
 from orb._constants import RAW_RESPONSE_HEADER
 from orb._exceptions import OrbError, APIStatusError, APITimeoutError, APIResponseValidationError
@@ -319,7 +320,8 @@ def test_validate_headers(self) -> None:
         assert request.headers.get("Authorization") == f"Bearer {api_key}"
 
         with pytest.raises(OrbError):
-            client2 = Orb(base_url=base_url, api_key=None, _strict_response_validation=True)
+            with update_env(**{"ORB_API_KEY": Omit()}):
+                client2 = Orb(base_url=base_url, api_key=None, _strict_response_validation=True)
             _ = client2
 
     def test_default_query_option(self) -> None:
@@ -1076,7 +1078,8 @@ def test_validate_headers(self) -> None:
         assert request.headers.get("Authorization") == f"Bearer {api_key}"
 
         with pytest.raises(OrbError):
-            client2 = AsyncOrb(base_url=base_url, api_key=None, _strict_response_validation=True)
+            with update_env(**{"ORB_API_KEY": Omit()}):
+                client2 = AsyncOrb(base_url=base_url, api_key=None, _strict_response_validation=True)
             _ = client2
 
     def test_default_query_option(self) -> None:
diff --git a/tests/utils.py b/tests/utils.py
index 4aa683f2..1fa786ba 100644
--- a/tests/utils.py
+++ b/tests/utils.py
@@ -8,7 +8,7 @@
 from datetime import date, datetime
 from typing_extensions import Literal, get_args, get_origin, assert_type
 
-from orb._types import NoneType
+from orb._types import Omit, NoneType
 from orb._utils import (
     is_dict,
     is_list,
@@ -139,11 +139,15 @@ def _assert_list_type(type_: type[object], value: object) -> None:
 
 
 @contextlib.contextmanager
-def update_env(**new_env: str) -> Iterator[None]:
+def update_env(**new_env: str | Omit) -> Iterator[None]:
     old = os.environ.copy()
 
     try:
-        os.environ.update(new_env)
+        for name, value in new_env.items():
+            if isinstance(value, Omit):
+                os.environ.pop(name, None)
+            else:
+                os.environ[name] = value
 
         yield None
     finally: