diff --git a/stubs/requests/requests/structures.pyi b/stubs/requests/requests/structures.pyi
index 93e343f9b170..f27fe70fd293 100644
--- a/stubs/requests/requests/structures.pyi
+++ b/stubs/requests/requests/structures.pyi
@@ -11,6 +11,7 @@ class CaseInsensitiveDict(MutableMapping[str, _VT], Generic[_VT]):
     def __iter__(self) -> Iterator[str]: ...
     def __len__(self) -> int: ...
     def copy(self) -> CaseInsensitiveDict[_VT]: ...
+    def update(self, data: Mapping[str, _VT] | Iterable[tuple[str, _VT]], **kwargs: _VT) -> None: ...
 
 class LookupDict(dict[str, _VT]):
     name: Any