diff --git a/src/finch/_utils/_reflection.py b/src/finch/_utils/_reflection.py
index 9a53c7bd..89aa712a 100644
--- a/src/finch/_utils/_reflection.py
+++ b/src/finch/_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/utils.py b/tests/utils.py
index 03639932..2af6d870 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 finch._types import NoneType
+from finch._types import Omit, NoneType
 from finch._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: