diff --git a/stdlib/@tests/test_cases/check_io.py b/stdlib/@tests/test_cases/check_io.py
index c3ee5aa4c6c0..7e2c8001f3a5 100644
--- a/stdlib/@tests/test_cases/check_io.py
+++ b/stdlib/@tests/test_cases/check_io.py
@@ -1,6 +1,6 @@
 from _io import BufferedReader, BufferedRWPair, BufferedWriter
 from gzip import GzipFile
-from io import FileIO, RawIOBase, TextIOWrapper
+from io import BufferedRandom, BytesIO, FileIO, RawIOBase, TextIOWrapper
 from socket import SocketIO
 from typing import Any
 from typing_extensions import assert_type
@@ -16,3 +16,23 @@
 assert_type(TextIOWrapper(FileIO("")).buffer, FileIO)
 assert_type(TextIOWrapper(FileIO(13)).detach(), FileIO)
 assert_type(TextIOWrapper(GzipFile("")).buffer, GzipFile)
+
+
+class Index:
+    def __index__(self) -> int:
+        return 1
+
+
+assert_type(FileIO("").seek(Index()), int)
+assert_type(BufferedReader(BytesIO()).seek(Index()), int)
+assert_type(BufferedWriter(BytesIO()).seek(Index()), int)
+assert_type(BufferedRandom(FileIO("")).seek(Index()), int)
+FileIO("").seek("1")  # type: ignore[arg-type]
+
+
+class NarrowBytesIO(BytesIO):
+    def seek(self, pos: int, whence: int = 0, /) -> int:
+        return super().seek(pos, whence)
+
+
+assert_type(NarrowBytesIO().seek(1), int)
diff --git a/stdlib/_io.pyi b/stdlib/_io.pyi
index 5e216123be98..9012e0fd5348 100644
--- a/stdlib/_io.pyi
+++ b/stdlib/_io.pyi
@@ -6,7 +6,7 @@ from collections.abc import Callable, Iterable, Iterator
 from io import BufferedIOBase, RawIOBase, TextIOBase, UnsupportedOperation as UnsupportedOperation
 from os import _Opener
 from types import TracebackType
-from typing import IO, Any, BinaryIO, Final, Generic, Literal, Protocol, TextIO, TypeVar, overload, type_check_only
+from typing import IO, Any, BinaryIO, Final, Generic, Literal, Protocol, SupportsIndex, TextIO, TypeVar, overload, type_check_only
 from typing_extensions import Self, disjoint_base
 
 _S = TypeVar("_S", bound=str)
@@ -107,7 +107,7 @@ class FileIO(RawIOBase, _RawIOBase, BinaryIO):  # type: ignore[misc]  # incompat
     ) -> None: ...
     @property
     def closefd(self) -> bool: ...
-    def seek(self, pos: int, whence: int = 0, /) -> int: ...
+    def seek(self, pos: SupportsIndex, whence: int = 0, /) -> int: ...
     def read(self, size: int | None = -1, /) -> bytes | MaybeNone: ...
 
 @disjoint_base
@@ -160,7 +160,7 @@ class BufferedReader(BufferedIOBase, _BufferedIOBase, BinaryIO, Generic[_Buffere
         def __init__(self, raw: _BufferedReaderStreamT, buffer_size: int = 8192) -> None: ...
 
     def peek(self, size: int = 0, /) -> bytes: ...
-    def seek(self, target: int, whence: int = 0, /) -> int: ...
+    def seek(self, target: SupportsIndex, whence: int = 0, /) -> int: ...
     def truncate(self, pos: int | None = None, /) -> int: ...
 
 @type_check_only
@@ -198,7 +198,7 @@ class BufferedWriter(BufferedIOBase, _BufferedIOBase, BinaryIO, Generic[_Buffere
         def __init__(self, raw: _BufferedWriterStreamT, buffer_size: int = 8192) -> None: ...
 
     def write(self, buffer: ReadableBuffer, /) -> int: ...
-    def seek(self, target: int, whence: int = 0, /) -> int: ...
+    def seek(self, target: SupportsIndex, whence: int = 0, /) -> int: ...
     def truncate(self, pos: int | None = None, /) -> int: ...
 
 @disjoint_base
@@ -211,7 +211,7 @@ class BufferedRandom(BufferedIOBase, _BufferedIOBase, BinaryIO):  # type: ignore
     else:
         def __init__(self, raw: RawIOBase, buffer_size: int = 8192) -> None: ...
 
-    def seek(self, target: int, whence: int = 0, /) -> int: ...  # stubtest needs this
+    def seek(self, target: SupportsIndex, whence: int = 0, /) -> int: ...  # stubtest needs this
     def peek(self, size: int = 0, /) -> bytes: ...
     def truncate(self, pos: int | None = None, /) -> int: ...