diff --git a/Doc/library/http.server.rst b/Doc/library/http.server.rst
index 1b00b09bf6da7f..b32a75ae589e53 100644
--- a/Doc/library/http.server.rst
+++ b/Doc/library/http.server.rst
@@ -167,6 +167,13 @@ provides three different variants:
       header (using :meth:`send_header`) in all of its responses to clients.
       For backwards compatibility, the setting defaults to ``'HTTP/1.0'``.
 
+   .. attribute:: default_content_type
+
+      Specifies the content-type header value sent when the MIME type
+      cannot be guessed from the file extension of the requested URL.
+      By default, it is set to ``'application/octet-stream'``.
+
+      .. versionadded:: next
    .. attribute:: MessageClass
 
       Specifies an :class:`email.message.Message`\ -like class to parse HTTP
@@ -524,6 +531,16 @@ The following options are accepted:
 
    .. versionadded:: 3.11
 
+.. option:: --default-content-type <content_type>
+
+   Specifies the Content-Type HTTP header. By default, the server uses the
+   MIME type ``'application/octet-stream'`` for the ``Content-Type`` header
+   when the content type cannot be guessed from the URL's extension (if any)::
+
+        python -m http.server --default-content-type text/html
+
+   .. versionadded:: next
+
 .. option:: --cgi
 
    :class:`CGIHTTPRequestHandler` can be enabled in the command line by passing
diff --git a/Lib/http/server.py b/Lib/http/server.py
index a90c8d34c394db..287712c42c2b48 100644
--- a/Lib/http/server.py
+++ b/Lib/http/server.py
@@ -269,6 +269,7 @@ class BaseHTTPRequestHandler(socketserver.StreamRequestHandler):
     # the client gets back when sending a malformed request line.
     # Most web servers default to HTTP 0.9, i.e. don't send a status line.
     default_request_version = "HTTP/0.9"
+    default_content_type = "application/octet-stream"
 
     def parse_request(self):
         """Parse a request (internal).
@@ -907,7 +908,7 @@ def guess_type(self, path):
         guess, _ = mimetypes.guess_file_type(path)
         if guess:
             return guess
-        return 'application/octet-stream'
+        return self.default_content_type
 
 
 # Utilities for CGIHTTPRequestHandler
@@ -1263,7 +1264,8 @@ def _get_best_family(*address):
 
 def test(HandlerClass=BaseHTTPRequestHandler,
          ServerClass=ThreadingHTTPServer,
-         protocol="HTTP/1.0", port=8000, bind=None):
+         protocol="HTTP/1.0", port=8000, bind=None,
+         content_type=BaseHTTPRequestHandler.default_content_type):
     """Test the HTTP request handler class.
 
     This runs an HTTP server on port 8000 (or the port argument).
@@ -1271,6 +1273,7 @@ def test(HandlerClass=BaseHTTPRequestHandler,
     """
     ServerClass.address_family, addr = _get_best_family(bind, port)
     HandlerClass.protocol_version = protocol
+    HandlerClass.default_content_type = content_type
     with ServerClass(addr, HandlerClass) as httpd:
         host, port = httpd.socket.getsockname()[:2]
         url_host = f'[{host}]' if ':' in host else host
@@ -1301,6 +1304,10 @@ def test(HandlerClass=BaseHTTPRequestHandler,
                         default='HTTP/1.0',
                         help='conform to this HTTP version '
                              '(default: %(default)s)')
+    parser.add_argument('--content-type',
+                        default=BaseHTTPRequestHandler.default_content_type,
+                        help='default content type for unknown extensions'
+                             '(default: %(default)s)')
     parser.add_argument('port', default=8000, type=int, nargs='?',
                         help='bind to this port '
                              '(default: %(default)s)')
@@ -1330,4 +1337,5 @@ def finish_request(self, request, client_address):
         port=args.port,
         bind=args.bind,
         protocol=args.protocol,
+        content_type=args.content_type,
     )
diff --git a/Misc/NEWS.d/next/Library/2023-12-25-19-14-07.gh-issue-113471.ZQMpbI.rst b/Misc/NEWS.d/next/Library/2023-12-25-19-14-07.gh-issue-113471.ZQMpbI.rst
new file mode 100644
index 00000000000000..99ba9bd1820fc1
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2023-12-25-19-14-07.gh-issue-113471.ZQMpbI.rst
@@ -0,0 +1,2 @@
+Allow :mod:`http.server` to set a default content-type when serving
+files with an unknown or missing extension.