diff --git a/patches/python3.9 b/patches/python3.9
new file mode 100755
index 0000000000000000000000000000000000000000..0c6f1c8e7b7dc134c126d88945ba2af844f97be0
--- /dev/null
+++ b/patches/python3.9
@@ -0,0 +1,122 @@
+#!/bin/sh
+set -e
+# #1004558
+patch -p1 << 'EOF'
+diff -Nru python3.9-3.9.10/debian/patches/reproducible-pyc.diff python3.9-3.9.10/debian/patches/reproducible-pyc.diff
+--- python3.9-3.9.10/debian/patches/reproducible-pyc.diff 1970-01-01 01:00:00.000000000 +0100
++++ python3.9-3.9.10/debian/patches/reproducible-pyc.diff 2022-02-05 07:52:33.000000000 +0100
+@@ -0,0 +1,105 @@
++From 36ae9beb04763d498df2114657bfbbcfe58bf913 Mon Sep 17 00:00:00 2001
++From: Brandt Bucher <brandt@python.org>
++Date: Mon, 23 Aug 2021 18:34:17 -0700
++Subject: [PATCH] Serialize frozenset elements deterministically
++
++---
++ Lib/test/test_marshal.py | 25 +++++++++++++++
++ .../2021-08-23-21-39-59.bpo-37596.ojRcwB.rst | 2 ++
++ Python/marshal.c | 32 +++++++++++++++++++
++ 3 files changed, 59 insertions(+)
++ create mode 100644 Misc/NEWS.d/next/Library/2021-08-23-21-39-59.bpo-37596.ojRcwB.rst
++
++diff --git a/Lib/test/test_marshal.py b/Lib/test/test_marshal.py
++index 7bcf8e8..8252be3 100644
++--- a/Lib/test/test_marshal.py
+++++ b/Lib/test/test_marshal.py
++@@ -318,6 +318,31 @@ class BugsTestCase(unittest.TestCase):
++ for i in range(len(data)):
++ self.assertRaises(EOFError, marshal.loads, data[0: i])
++
+++ def test_deterministic_sets(self):
+++ # bpo-37596: To support reproducible builds, sets and frozensets need to
+++ # have their elements serialized in a consistent order (even when they
+++ # have been scrambled by hash randomization):
+++ for kind in ("set", "frozenset"):
+++ for elements in (
+++ "float('nan'), b'a', b'b', b'c', 'x', 'y', 'z'",
+++ # Also test for bad interactions with backreferencing:
+++ "('string', 1), ('string', 2), ('string', 3)",
+++ ):
+++ s = f"{kind}([{elements}])"
+++ with self.subTest(s):
+++ # First, make sure that our test case still has different
+++ # orders under hash seeds 0 and 1. If this check fails, we
+++ # need to update this test with different elements:
+++ args = ["-c", f"print({s})"]
+++ _, repr_0, _ = assert_python_ok(*args, PYTHONHASHSEED="0")
+++ _, repr_1, _ = assert_python_ok(*args, PYTHONHASHSEED="1")
+++ self.assertNotEqual(repr_0, repr_1)
+++ # Then, perform the actual test:
+++ args = ["-c", f"import marshal; print(marshal.dumps({s}))"]
+++ _, dump_0, _ = assert_python_ok(*args, PYTHONHASHSEED="0")
+++ _, dump_1, _ = assert_python_ok(*args, PYTHONHASHSEED="1")
+++ self.assertEqual(dump_0, dump_1)
+++
++ LARGE_SIZE = 2**31
++ pointer_size = 8 if sys.maxsize > 0xFFFFFFFF else 4
++
++diff --git a/Misc/NEWS.d/next/Library/2021-08-23-21-39-59.bpo-37596.ojRcwB.rst b/Misc/NEWS.d/next/Library/2021-08-23-21-39-59.bpo-37596.ojRcwB.rst
++new file mode 100644
++index 0000000..81fdfeb
++--- /dev/null
+++++ b/Misc/NEWS.d/next/Library/2021-08-23-21-39-59.bpo-37596.ojRcwB.rst
++@@ -0,0 +1,2 @@
+++Ensure that :class:`set` and :class:`frozenset` objects are always
+++:mod:`marshalled <marshal>` reproducibly.
++diff --git a/Python/marshal.c b/Python/marshal.c
++index 4125240..6bd4537 100644
++--- a/Python/marshal.c
+++++ b/Python/marshal.c
++@@ -502,9 +502,41 @@ w_complex_object(PyObject *v, char flag, WFILE *p)
++ W_TYPE(TYPE_SET, p);
++ n = PySet_GET_SIZE(v);
++ W_SIZE(n, p);
+++ // bpo-37596: To support reproducible builds, sets and frozensets need
+++ // to have their elements serialized in a consistent order (even when
+++ // they have been scrambled by hash randomization). To ensure this, we
+++ // use an order equivalent to sorted(v, key=marshal.dumps):
+++ PyObject *pairs = PyList_New(0);
+++ if (pairs == NULL) {
+++ p->error = WFERR_NOMEMORY;
+++ return;
+++ }
++ while (_PySet_NextEntry(v, &pos, &value, &hash)) {
+++ PyObject *dump = PyMarshal_WriteObjectToString(value, p->version);
+++ if (dump == NULL) {
+++ p->error = WFERR_UNMARSHALLABLE;
+++ goto anyset_done;
+++ }
+++ PyObject *pair = PyTuple_Pack(2, dump, value);
+++ Py_DECREF(dump);
+++ if (pair == NULL || PyList_Append(pairs, pair)) {
+++ p->error = WFERR_NOMEMORY;
+++ Py_XDECREF(pair);
+++ goto anyset_done;
+++ }
+++ Py_DECREF(pair);
+++ }
+++ if (PyList_Sort(pairs)) {
+++ p->error = WFERR_NOMEMORY;
+++ goto anyset_done;
+++ }
+++ for (Py_ssize_t i = 0; i < n; i++) {
+++ PyObject *pair = PyList_GET_ITEM(pairs, i);
+++ value = PyTuple_GET_ITEM(pair, 1);
++ w_object(value, p);
++ }
+++ anyset_done:
+++ Py_DECREF(pairs);
++ }
++ else if (PyCode_Check(v)) {
++ PyCodeObject *co = (PyCodeObject *)v;
++--
++2.33.0
++
+diff -Nru python3.9-3.9.10/debian/patches/series python3.9-3.9.10/debian/patches/series
+--- python3.9-3.9.10/debian/patches/series 2022-01-16 17:07:24.000000000 +0100
++++ python3.9-3.9.10/debian/patches/series 2022-02-05 07:52:42.000000000 +0100
+@@ -40,3 +40,4 @@
+ sphinx3.diff
+ mpdecimal-2.5.1.diff
+ destshared-location.diff
++reproducible-pyc.diff
+EOF