diff --git a/pydantic_converter_v1/worker.py b/pydantic_converter_v1/worker.py
index 5ff65e1e2..3753aa0b5 100644
--- a/pydantic_converter_v1/worker.py
+++ b/pydantic_converter_v1/worker.py
@@ -49,18 +49,11 @@ async def run(self, models: List[MyPydanticModel]) -> List[MyPydanticModel]:
 # workflows, we're going to remove datetime module restrictions. See sdk-python
 # README's discussion of known sandbox issues for more details.
 def new_sandbox_runner() -> SandboxedWorkflowRunner:
-    # TODO(cretz): Use with_child_unrestricted when https://github.com/temporalio/sdk-python/issues/254
-    # is fixed and released
-    invalid_module_member_children = dict(
-        SandboxRestrictions.invalid_module_members_default.children
-    )
-    del invalid_module_member_children["datetime"]
     return SandboxedWorkflowRunner(
         restrictions=dataclasses.replace(
             SandboxRestrictions.default,
-            invalid_module_members=dataclasses.replace(
-                SandboxRestrictions.invalid_module_members_default,
-                children=invalid_module_member_children,
+            invalid_module_members=SandboxRestrictions.invalid_module_members_default.with_child_unrestricted(
+                "datetime"
             ),
         )
     )