diff --git a/.github/workflows/build-zlib-ng.yml b/.github/workflows/build-zlib-ng.yml
new file mode 100644
index 000000000..702c0a7e3
--- /dev/null
+++ b/.github/workflows/build-zlib-ng.yml
@@ -0,0 +1,94 @@
+# SPDX-FileCopyrightText: 2026 The RISE Project
+# SPDX-License-Identifier: MIT
+---
+# Based on upstream's own deploy job:
+# https://github.com/pycompression/python-zlib-ng/blob/v1.0.0/.github/workflows/ci.yml
+name: Build zlib-ng wheels (riscv64)
+
+on:
+  workflow_dispatch:
+    inputs:
+      version:
+        description: 'zlib-ng version to build (git tag without the leading v, e.g. 1.0.0)'
+        required: true
+        default: '1.0.0'
+  pull_request:
+    paths:
+      - '.github/workflows/build-zlib-ng.yml'
+
+concurrency:
+  group: ${{ github.workflow }}-${{ inputs.version || '1.0.0' }}-${{ github.head_ref || github.run_id }}
+  cancel-in-progress: true
+
+permissions:
+  contents: read  # to fetch code (actions/checkout)
+
+env:
+  # `inputs.version` is empty on pull_request events; default to 1.0.0 there.
+  ZLIB_NG_VERSION: ${{ inputs.version || '1.0.0' }}
+  MANYLINUX_RISCV64_IMAGE: quay.io/pypa/manylinux_2_39_riscv64
+  MUSLLINUX_RISCV64_IMAGE: quay.io/pypa/musllinux_1_2_riscv64
+
+jobs:
+  setup:
+    uses: $/.github/workflows/_setup.yml
+
+  build_wheels:
+    needs: [setup]
+    name: Build zlib-ng ${{ inputs.version || '1.0.0' }} ${{ matrix.python }}-${{ matrix.libc }}_riscv64
+    runs-on: ubuntu-24.04-riscv
+    timeout-minutes: 60
+    strategy:
+      fail-fast: false
+      matrix:
+        python: ["cp312", "cp313", "cp314", "cp314t"]
+        libc: [manylinux, musllinux]
+
+    steps:
+      - name: Checkout zlib-ng v${{ env.ZLIB_NG_VERSION }}
+        uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1  # v7.0.1
+        with:
+          repository: pycompression/python-zlib-ng
+          ref: v${{ env.ZLIB_NG_VERSION }}
+          submodules: recursive
+          persist-credentials: false
+
+      - name: Checkout python-wheels
+        uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1  # v7.0.1
+        with:
+          path: python-wheels
+          persist-credentials: false
+
+      - name: Patch zlib-ng source
+        run: git apply python-wheels/patches/zlib-ng/${{ env.ZLIB_NG_VERSION }}/00*.patch
+
+      - name: Build wheels
+        uses: pypa/cibuildwheel@1828c10ab37f080699c7b81cea34097c684a7074  # v4.2.0
+        with:
+          output-dir: wheelhouse/
+        env:
+          CIBW_BUILD: ${{ matrix.python }}-${{ matrix.libc }}_riscv64
+          CIBW_MANYLINUX_RISCV64_IMAGE: ${{ env.MANYLINUX_RISCV64_IMAGE }}
+          CIBW_MUSLLINUX_RISCV64_IMAGE: ${{ env.MUSLLINUX_RISCV64_IMAGE }}
+          CIBW_ENVIRONMENT: CFLAGS="-O3 -DNDEBUG"
+          CIBW_TEST_REQUIRES: pytest
+          CIBW_TEST_COMMAND: >-
+            pytest {project}/tests/test_zlib_compliance.py
+            {project}/tests/test_gzip_compliance.py
+            {project}/tests/test_gzip_ng.py
+
+      - uses: actions/upload-artifact@043fb46d1a93c77aae656e7c1c64a875d1fc6a0a  # v7.0.1
+        with:
+          name: zlib-ng-${{ env.ZLIB_NG_VERSION }}-${{ matrix.python }}-${{ matrix.libc }}_riscv64
+          path: wheelhouse/*.whl
+          if-no-files-found: error
+
+  publish:
+    name: Publish zlib-ng ${{ inputs.version || '1.0.0' }}
+    needs: [setup, build_wheels]
+    permissions:
+      contents: write
+      pull-requests: write
+    uses: $/.github/workflows/_publish-wheel.yml
+    with:
+      artifact-pattern: zlib-ng-${{ inputs.version || '1.0.0' }}-*riscv64
diff --git a/patches/zlib-ng/1.0.0/0001-setup-disable-RVV-on-riscv64.patch b/patches/zlib-ng/1.0.0/0001-setup-disable-RVV-on-riscv64.patch
new file mode 100644
index 000000000..239f41041
--- /dev/null
+++ b/patches/zlib-ng/1.0.0/0001-setup-disable-RVV-on-riscv64.patch
@@ -0,0 +1,65 @@
+From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
+From: Ludovic Henry <git@ludovic.dev>
+Date: Sun, 6 Sep 2026 14:10:34 +0200
+Subject: [PATCH] setup: disable RVV on riscv64
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+zlib-ng's riscv_check_features() runtime-detects the V extension via
+getauxval(AT_HWCAP), and when it believes V is present it executes an
+inline vsetvli/csrr probe to confirm vector length and tail/mask-agnostic
+support before turning on the RVV-accelerated deflate/inflate paths
+(adler32_rvv, chunkset_rvv, compare256_rvv, slide_hash_rvv).
+
+On the riscv64 CI hardware this repo builds wheels on, that vsetvli probe
+itself raises SIGILL (Illegal instruction) — the very first RVV
+instruction zlib-ng's own feature check executes crashes the process,
+before any deflate/inflate call is made. Every test that imports
+zlib_ng (test_zlib_compliance.py, test_gzip_compliance.py,
+test_gzip_ng.py) segfaults the same way at zng_deflateInit2.
+
+setup.py's Linux build path drives zlib-ng's autoconf-style ./configure
+script directly (not CMake — that path is Windows-only) and exposes no
+environment-variable hook to pass extra configure flags, so the only way
+to reach configure's own --without-rvv switch is to have setup.py add it
+itself. Guard it on platform.machine() so non-riscv builds (and riscv
+hardware where this is eventually fixed/verified) are unaffected.
+
+This falls back zlib-ng to its portable C RVV-free code paths, still
+much faster than not shipping zlib-ng-accelerated zlib/gzip at all.
+
+Upstream-Status: Inappropriate [riscv64 CI-hardware-only RVV runtime-detection SIGILL; not a defect in this project]
+---
+ setup.py | 8 +++++++-
+ 1 file changed, 7 insertions(+), 1 deletion(-)
+
+diff --git a/setup.py b/setup.py
+index f58cbf8..d9d3109 100644
+--- a/setup.py
++++ b/setup.py
+@@ -7,6 +7,7 @@
+
+ import functools
+ import os
++import platform
+ import shutil
+ import subprocess
+ import sys
+@@ -108,7 +109,12 @@ def build_zlib_ng():
+         make_program = "gmake" if shutil.which("gmake") else "make"
+         subprocess.run([make_program, "libz-ng.a"], **run_args)
+     elif sys.platform == "linux":
+-        subprocess.run([os.path.join(build_dir, "configure")], **run_args)
++        configure_args = [os.path.join(build_dir, "configure")]
++        if platform.machine() in ("riscv64", "riscv32"):
++            # riscv_check_features()'s vsetvli runtime probe SIGILLs on
++            # this hardware; disable RVV rather than crash every caller.
++            configure_args.append("--without-rvv")
++        subprocess.run(configure_args, **run_args)
+         subprocess.run(["make", "libz-ng.a", "-j", str(cpu_count)], **run_args)
+     else:
+         subprocess.run(["cmake", build_dir], **run_args)
+--
+2.50.1 (Apple Git-155)
+