From 7557b03da53a51a21dbd66ee8206755fdcd0d728 Mon Sep 17 00:00:00 2001
From: "J. Nick Koston" <nick@koston.org>
Date: Wed, 4 Dec 2024 13:20:52 -0600
Subject: [PATCH] Fix deprecated calls to `guess_type` for paths with Python
 3.13 (#10102)

---
 CHANGES/10102.bugfix.rst    | 1 +
 aiohttp/payload.py          | 7 ++++++-
 aiohttp/web_fileresponse.py | 9 ++++++---
 3 files changed, 13 insertions(+), 4 deletions(-)
 create mode 100644 CHANGES/10102.bugfix.rst

diff --git a/CHANGES/10102.bugfix.rst b/CHANGES/10102.bugfix.rst
new file mode 100644
index 00000000000..86dda8684dd
--- /dev/null
+++ b/CHANGES/10102.bugfix.rst
@@ -0,0 +1 @@
+Replaced deprecated call to :func:`mimetypes.guess_type` with :func:`mimetypes.guess_file_type` when using Python 3.13+ -- by :user:`bdraco`.
diff --git a/aiohttp/payload.py b/aiohttp/payload.py
index 1bc7f27de8b..55a7a677f49 100644
--- a/aiohttp/payload.py
+++ b/aiohttp/payload.py
@@ -4,6 +4,7 @@
 import json
 import mimetypes
 import os
+import sys
 import warnings
 from abc import ABC, abstractmethod
 from itertools import chain
@@ -169,7 +170,11 @@ def __init__(
             assert isinstance(content_type, str)
             self._headers[hdrs.CONTENT_TYPE] = content_type
         elif self._filename is not None:
-            content_type = mimetypes.guess_type(self._filename)[0]
+            if sys.version_info >= (3, 13):
+                guesser = mimetypes.guess_file_type
+            else:
+                guesser = mimetypes.guess_type
+            content_type = guesser(self._filename)[0]
             if content_type is None:
                 content_type = self._default_content_type
             self._headers[hdrs.CONTENT_TYPE] = content_type
diff --git a/aiohttp/web_fileresponse.py b/aiohttp/web_fileresponse.py
index daadda9a207..dacbb2b5892 100644
--- a/aiohttp/web_fileresponse.py
+++ b/aiohttp/web_fileresponse.py
@@ -1,6 +1,7 @@
 import asyncio
 import os
 import pathlib
+import sys
 from contextlib import suppress
 from mimetypes import MimeTypes
 from stat import S_ISREG
@@ -314,9 +315,11 @@ async def prepare(self, request: "BaseRequest") -> Optional[AbstractStreamWriter
         # extension of the request path. The encoding returned by guess_type
         #  can be ignored since the map was cleared above.
         if hdrs.CONTENT_TYPE not in self.headers:
-            self.content_type = (
-                CONTENT_TYPES.guess_type(self._path)[0] or FALLBACK_CONTENT_TYPE
-            )
+            if sys.version_info >= (3, 13):
+                guesser = CONTENT_TYPES.guess_file_type
+            else:
+                guesser = CONTENT_TYPES.guess_type
+            self.content_type = guesser(self._path)[0] or FALLBACK_CONTENT_TYPE
 
         if file_encoding:
             self.headers[hdrs.CONTENT_ENCODING] = file_encoding