From c642dc83cc6da32f255b1537959b10f320ceff92 Mon Sep 17 00:00:00 2001
From: "Miss Islington (bot)"
 <31488909+miss-islington@users.noreply.github.com>
Date: Sat, 18 Jul 2026 09:21:46 +0200
Subject: [PATCH] [3.15] gh-150583: Fix zstd compression level with digested
 ZstdDict (GH-150586) (#153883)

gh-150583: Fix zstd compression level with digested ZstdDict (GH-150586)
(cherry picked from commit 0983642c966d9c536416101e99b7d2b085483847)

Co-authored-by: Rogdham <3994389+Rogdham@users.noreply.github.com>
---
 .../next/Library/2026-06-03-19-35-32.gh-issue-150583.dedI24.rst | 2 ++
 Modules/_zstd/compressor.c                                      | 1 +
 2 files changed, 3 insertions(+)
 create mode 100644 Misc/NEWS.d/next/Library/2026-06-03-19-35-32.gh-issue-150583.dedI24.rst

diff --git a/Misc/NEWS.d/next/Library/2026-06-03-19-35-32.gh-issue-150583.dedI24.rst b/Misc/NEWS.d/next/Library/2026-06-03-19-35-32.gh-issue-150583.dedI24.rst
new file mode 100644
index 000000000000..edb551b3c3c8
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2026-06-03-19-35-32.gh-issue-150583.dedI24.rst
@@ -0,0 +1,2 @@
+Correctly set the default compression level in :mod:`compression.zstd` when passing a digested
+dictionary during compression.
diff --git a/Modules/_zstd/compressor.c b/Modules/_zstd/compressor.c
index b2eb22d9ec8a..894568fce28d 100644
--- a/Modules/_zstd/compressor.c
+++ b/Modules/_zstd/compressor.c
@@ -347,6 +347,7 @@ _zstd_ZstdCompressor_new_impl(PyTypeObject *type, PyObject *level,
     }
 
     self->use_multithread = 0;
+    self->compression_level = ZSTD_CLEVEL_DEFAULT;
     self->dict = NULL;
     self->lock = (PyMutex){0};
 
-- 
2.47.3