diff --git a/Lib/socket.py b/Lib/socket.py
index 727b0e75f03595..e81940abd5b031 100644
--- a/Lib/socket.py
+++ b/Lib/socket.py
@@ -78,7 +78,7 @@
 IntEnum._convert_(
         'AddressFamily',
         __name__,
-        lambda C: C.isupper() and C.startswith('AF_'))
+        lambda C: C.startswith('AF_'))
 
 IntEnum._convert_(
         'SocketKind',
diff --git a/Lib/test/test_socket.py b/Lib/test/test_socket.py
index 3dd67b2a2aba97..f455c5b0a2ea7f 100644
--- a/Lib/test/test_socket.py
+++ b/Lib/test/test_socket.py
@@ -2138,11 +2138,15 @@ def test_addressfamily_enum(self):
         import _socket, enum
         CheckedAddressFamily = enum._old_convert_(
                 enum.IntEnum, 'AddressFamily', 'socket',
-                lambda C: C.isupper() and C.startswith('AF_'),
+                lambda C: C.startswith('AF_'),
                 source=_socket,
                 )
         enum._test_simple_enum(CheckedAddressFamily, socket.AddressFamily)
 
+    @unittest.skipUnless(hasattr(_socket, 'AF_DECnet'), 'AF_DECnet required.')
+    def test_addressfamily_enum_decnet(self):
+        assert hasattr(socket.AddressFamily, 'AF_DECnet')
+
     def test_socketkind_enum(self):
         import _socket, enum
         CheckedSocketKind = enum._old_convert_(
diff --git a/Misc/NEWS.d/next/Library/2024-12-02-21-19-53.gh-issue-127544.N7uEsX.rst b/Misc/NEWS.d/next/Library/2024-12-02-21-19-53.gh-issue-127544.N7uEsX.rst
new file mode 100644
index 00000000000000..f735f7bf54fbdd
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2024-12-02-21-19-53.gh-issue-127544.N7uEsX.rst
@@ -0,0 +1,2 @@
+Ensure that ``AF_DECnet`` is part of the :class:`!socket.AddressFamily`
+enum, when available.