diff --git a/src/anthropic/_utils/__init__.py b/src/anthropic/_utils/__init__.py
index 56978941..31b5b227 100644
--- a/src/anthropic/_utils/__init__.py
+++ b/src/anthropic/_utils/__init__.py
@@ -6,6 +6,7 @@
     is_list as is_list,
     is_given as is_given,
     is_tuple as is_tuple,
+    lru_cache as lru_cache,
     is_mapping as is_mapping,
     is_tuple_t as is_tuple_t,
     parse_date as parse_date,
diff --git a/src/anthropic/_utils/_utils.py b/src/anthropic/_utils/_utils.py
index 93c95517..5123a230 100644
--- a/src/anthropic/_utils/_utils.py
+++ b/src/anthropic/_utils/_utils.py
@@ -389,3 +389,11 @@ def get_async_library() -> str:
         return sniffio.current_async_library()
     except Exception:
         return "false"
+
+
+def lru_cache(*, maxsize: int | None = 128) -> Callable[[CallableT], CallableT]:
+    """A version of functools.lru_cache that retains the type signature
+    for the wrapped function arguments.
+    """
+    wrapper = functools.lru_cache(maxsize=maxsize)
+    return cast(Any, wrapper)  # type: ignore[no-any-return]
diff --git a/src/anthropic/lib/bedrock/_auth.py b/src/anthropic/lib/bedrock/_auth.py
index caae0100..95c820f6 100644
--- a/src/anthropic/lib/bedrock/_auth.py
+++ b/src/anthropic/lib/bedrock/_auth.py
@@ -1,10 +1,11 @@
 from __future__ import annotations
 
 from typing import TYPE_CHECKING
-from functools import lru_cache
 
 import httpx
 
+from ..._utils import lru_cache
+
 if TYPE_CHECKING:
     import boto3
 
@@ -42,9 +43,9 @@ def get_auth_headers(
     from botocore.awsrequest import AWSRequest
 
     session = _get_session(
-        region_name=region,
-        aws_access_key_id=aws_access_key,
-        aws_secret_access_key=aws_secret_key,
+        region=region,
+        aws_access_key=aws_access_key,
+        aws_secret_key=aws_secret_key,
         aws_session_token=aws_session_token,
     )