diff --git a/.github/workflows/build-libsass.yml b/.github/workflows/build-libsass.yml
new file mode 100644
index 000000000..f9ce151b3
--- /dev/null
+++ b/.github/workflows/build-libsass.yml
@@ -0,0 +1,105 @@
+# SPDX-FileCopyrightText: 2026 The RISE Project
+# SPDX-License-Identifier: MIT
+---
+# This workflow is based on: https://github.com/sass/libsass-python/blob/0.23.0/.github/workflows/main.yml
+name: Build libsass wheels (riscv64)
+
+on:
+  workflow_dispatch:
+    inputs:
+      version:
+        description: 'libsass version to build (git tag, e.g. 0.23.0)'
+        required: true
+        default: '0.23.0'
+  pull_request:
+    paths:
+      - '.github/workflows/build-libsass.yml'
+      - 'patches/libsass/**'
+
+concurrency:
+  group: ${{ github.workflow }}-${{ inputs.version || '0.23.0' }}-${{ github.head_ref || github.run_id }}
+  cancel-in-progress: true
+
+permissions:
+  contents: read  # to fetch code (actions/checkout)
+
+env:
+  LIBSASS_VERSION: ${{ inputs.version || '0.23.0' }}
+  MANYLINUX_RISCV64_IMAGE: quay.io/pypa/manylinux_2_39_riscv64
+
+jobs:
+  setup:
+    uses: $/.github/workflows/_setup.yml
+
+  build_wheels:
+    needs: [setup]
+    name: Build libsass ${{ inputs.version || '0.23.0' }} cp312-abi3-manylinux_riscv64
+    runs-on: ubuntu-24.04-riscv
+    timeout-minutes: 60
+
+    steps:
+      - name: Checkout libsass-python v${{ env.LIBSASS_VERSION }}
+        uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1  # v7.0.1
+        with:
+          repository: sass/libsass-python
+          ref: ${{ env.LIBSASS_VERSION }}
+          submodules: true
+          persist-credentials: false
+
+      - name: Checkout python-wheels
+        uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1  # v7.0.1
+        with:
+          path: python-wheels
+          persist-credentials: false
+
+      # setup.cfg's `license_files = LICENSE` is an explicit list, which turns off
+      # setuptools' default glob (gotcha 57); the vendored libsass submodule (compiled
+      # straight into the extension) carries its own separate MIT licence (gotcha 32).
+      - name: Stage the libsass licence
+        run: |
+          cp libsass/LICENSE LICENSE.libsass
+          sed -i '/^license_files = LICENSE$/a\    LICENSE.libsass' setup.cfg
+
+      - name: Patch libsass-python source
+        run: git apply python-wheels/patches/libsass/${{ env.LIBSASS_VERSION }}/*.patch
+
+      - uses: pypa/cibuildwheel@1828c10ab37f080699c7b81cea34097c684a7074  # v4.2.0
+        with:
+          output-dir: wheelhouse/
+        env:
+          CIBW_ARCHS: riscv64
+          # setup.py's bdist_wheel override sets py_limited_api to the building
+          # interpreter's own version, so cp312 (our floor) becomes the abi3 tag;
+          # the later entries build nothing, they just re-test the one wheel.
+          # cp314t is skipped: setup.py forces py_limited_api unconditionally for
+          # CPython with no Py_GIL_DISABLED guard, same shape upstream's own zopfli
+          # sibling hits (build-zopfli.yml) - free-threaded builds don't support abi3.
+          CIBW_BUILD: >-
+            cp312-manylinux_riscv64 cp313-manylinux_riscv64 cp314-manylinux_riscv64
+          CIBW_MANYLINUX_RISCV64_IMAGE: ${{ env.MANYLINUX_RISCV64_IMAGE }}
+          # sassutils/wsgi.py imports pkg_resources, which setuptools 82 deleted
+          # outright (gotcha 29); pin below that floor for the test env only.
+          CIBW_TEST_REQUIRES: pytest werkzeug>=0.9 setuptools<82
+          # sasstests.py opens fixtures ("test/a.scss") relative to the process cwd,
+          # not __file__; cibuildwheel runs test-command from an empty temp dir, so
+          # stage the file plus its fixture dirs there and run against them, leaving
+          # sass.py/sassutils unstaged so the import resolves to the installed wheel
+          # (gotcha 36).
+          CIBW_TEST_SOURCES: sasstests.py test testpkg
+          CIBW_TEST_COMMAND: pytest sasstests.py -v
+
+      - uses: actions/upload-artifact@043fb46d1a93c77aae656e7c1c64a875d1fc6a0a  # v7.0.1
+        with:
+          name: libsass-${{ env.LIBSASS_VERSION }}-cp312-abi3-manylinux_riscv64
+          path: wheelhouse/*.whl
+          if-no-files-found: error
+
+  publish:
+    name: Publish libsass ${{ inputs.version || '0.23.0' }}
+    needs: [setup, build_wheels]
+    permissions:
+      contents: write
+      pull-requests: write
+    uses: $/.github/workflows/_publish-wheel.yml
+    with:
+      artifact-pattern: libsass-${{ inputs.version || '0.23.0' }}-*-manylinux_riscv64
diff --git a/patches/libsass/0.23.0/0001-Give-the-internal-enum-dict-init-module-helpers-inte.patch b/patches/libsass/0.23.0/0001-Give-the-internal-enum-dict-init-module-helpers-inte.patch
new file mode 100644
index 000000000..c735f276b
--- /dev/null
+++ b/patches/libsass/0.23.0/0001-Give-the-internal-enum-dict-init-module-helpers-inte.patch
@@ -0,0 +1,48 @@
+From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
+From: Ludovic Henry <git@ludovic.dev>
+Date: Sun, 6 Sep 2026 14:09:19 +0200
+Subject: Give the internal enum-dict/init-module helpers internal linkage
+
+Upstream-Status: To upstream [not yet submitted; upstream's own CI does not run abi3audit so this leak is invisible to them]
+
+PySass_make_enum_dict() and PySass_init_module() are declared with
+default (extern) visibility but are only ever called from within
+_sass.c itself. Because the extension is built with Py_LIMITED_API
+(setup.py sets py_limited_api=True), abi3audit --strict flags both as
+non-abi3 symbols leaking from the .abi3.so: a wheel claiming forward
+ABI compatibility must not export symbols outside the stable-ABI
+allowlist, since a symbol like this could collide with another
+extension or a future CPython internal of the same name. Only
+PyInit__sass needs to be visible; mark both helpers static so the
+compiler gives them internal linkage instead.
+
+Signed-off-by: Ludovic Henry <git@ludovic.dev>
+---
+ _sass.c | 4 ++--
+ 1 file changed, 2 insertions(+), 2 deletions(-)
+
+diff --git a/_sass.c b/_sass.c
+index a3bec29..6a57ba8 100644
+--- a/_sass.c
++++ b/_sass.c
+@@ -652,7 +652,7 @@ static PyMethodDef PySass_methods[] = {
+ 
+ static char PySass_doc[] = "The thin binding of libsass for Python.";
+ 
+-PyObject* PySass_make_enum_dict() {
++static PyObject* PySass_make_enum_dict() {
+     PyObject* dct = PyDict_New();
+     PyDict_SetItemString(dct, "nested", PyLong_FromLong(SASS_STYLE_NESTED));
+     PyDict_SetItemString(dct, "expanded", PyLong_FromLong(SASS_STYLE_EXPANDED));
+@@ -661,7 +661,7 @@ PyObject* PySass_make_enum_dict() {
+     return dct;
+ }
+ 
+-void PySass_init_module(PyObject *module) {
++static void PySass_init_module(PyObject *module) {
+     PyModule_AddObject(module, "OUTPUT_STYLES", PySass_make_enum_dict());
+     PyModule_AddObject(module, "libsass_version", PyUnicode_FromString(libsass_version()));
+ }
+-- 
+2.50.1 (Apple Git-155)
+