diff --git a/rapids_build_backend/config.py b/rapids_build_backend/config.py
index 66f82c7..d1a5798 100644
--- a/rapids_build_backend/config.py
+++ b/rapids_build_backend/config.py
@@ -1,7 +1,7 @@
 # Copyright (c) 2024, NVIDIA CORPORATION.
 
 import os
-from typing import TYPE_CHECKING
+from typing import TYPE_CHECKING, Union
 
 from .utils import _get_pyproject
 
@@ -9,13 +9,15 @@
     from typing import Callable
 
     # config options can be one of these types...
-    config_val_type = str | bool | None
+    config_val_type = Union[str, bool, None]
 
     # ... or a callable that returns one of those or some other mutable types
     mutable_config_val_type = list[str]
-    config_val_callable = Callable[[], config_val_type | mutable_config_val_type]
+    config_val_callable = Callable[[], Union[config_val_type, mutable_config_val_type]]
 
-    config_options_type = dict[str, tuple[config_val_type | config_val_callable, bool]]
+    config_options_type = dict[
+        str, tuple[Union[config_val_type, config_val_callable], bool]
+    ]
 
 
 class Config:
diff --git a/rapids_build_backend/impls.py b/rapids_build_backend/impls.py
index c15bc28..d4d8450 100644
--- a/rapids_build_backend/impls.py
+++ b/rapids_build_backend/impls.py
@@ -7,6 +7,7 @@
 from contextlib import contextmanager
 from functools import lru_cache
 from importlib import import_module
+from typing import Union
 
 import rapids_dependency_file_generator
 import tomli_w
@@ -99,7 +100,7 @@ def _get_cuda_suffix(require_cuda=False) -> str:
 
 
 @lru_cache
-def _get_git_commit() -> str | None:
+def _get_git_commit() -> Union[str, None]:
     """Get the current git commit.
 
     Returns None if git is not in the PATH or if it fails to find the commit.