diff --git a/requirements-dev.lock b/requirements-dev.lock
index b6e5d7dc7a..802f827d44 100644
--- a/requirements-dev.lock
+++ b/requirements-dev.lock
@@ -63,7 +63,7 @@ pydantic==2.7.1
     # via openai
 pydantic-core==2.18.2
     # via pydantic
-pyright==1.1.359
+pyright==1.1.364
 pytest==7.1.1
     # via pytest-asyncio
 pytest-asyncio==0.21.1
diff --git a/src/openai/_utils/_utils.py b/src/openai/_utils/_utils.py
index 17904ce60d..34797c2905 100644
--- a/src/openai/_utils/_utils.py
+++ b/src/openai/_utils/_utils.py
@@ -20,7 +20,7 @@
 
 import sniffio
 
-from .._types import Headers, NotGiven, FileTypes, NotGivenOr, HeadersLike
+from .._types import NotGiven, FileTypes, NotGivenOr, HeadersLike
 from .._compat import parse_date as parse_date, parse_datetime as parse_datetime
 
 _T = TypeVar("_T")
@@ -370,7 +370,6 @@ def file_from_path(path: str) -> FileTypes:
 def get_required_header(headers: HeadersLike, header: str) -> str:
     lower_header = header.lower()
     if isinstance(headers, Mapping):
-        headers = cast(Headers, headers)
         for k, v in headers.items():
             if k.lower() == lower_header and isinstance(v, str):
                 return v