diff --git a/.github/workflows/build-pystemmer.yml b/.github/workflows/build-pystemmer.yml
new file mode 100644
index 000000000..ded62bc99
--- /dev/null
+++ b/.github/workflows/build-pystemmer.yml
@@ -0,0 +1,89 @@
+# SPDX-FileCopyrightText: 2026 The RISE Project
+# SPDX-License-Identifier: MIT
+---
+# This workflow is based on the `build` job of
+# https://github.com/snowballstem/pystemmer/blob/v3.1.0/.github/workflows/ci.yml
+name: Build pystemmer wheels (riscv64)
+
+on:
+  workflow_dispatch:
+    inputs:
+      version:
+        description: 'pystemmer version to build (git tag, e.g. 3.1.0)'
+        required: true
+        default: '3.1.0'
+  pull_request:
+    paths:
+      - '.github/workflows/build-pystemmer.yml'
+
+concurrency:
+  group: ${{ github.workflow }}-${{ inputs.version || '3.1.0' }}-${{ github.head_ref || github.run_id }}
+  cancel-in-progress: true
+
+permissions:
+  contents: read  # to fetch code (actions/checkout)
+
+env:
+  PYSTEMMER_VERSION: ${{ inputs.version || '3.1.0' }}
+  MANYLINUX_RISCV64_IMAGE: quay.io/pypa/manylinux_2_39_riscv64
+
+jobs:
+  setup:
+    uses: $/.github/workflows/_setup.yml
+
+  build_wheels:
+    needs: [setup]
+    name: Build pystemmer ${{ inputs.version || '3.1.0' }} ${{ matrix.python }}-manylinux_riscv64
+    runs-on: ubuntu-24.04-riscv
+    strategy:
+      fail-fast: false
+      matrix:
+        python:
+          - "cp312"
+          - "cp313"
+          - "cp314"
+          - "cp314t"
+
+    steps:
+      - name: Checkout pystemmer v${{ env.PYSTEMMER_VERSION }}
+        uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1  # v7.0.1
+        with:
+          repository: snowballstem/pystemmer
+          ref: v${{ env.PYSTEMMER_VERSION }}
+          persist-credentials: false
+
+      - name: Build wheels
+        uses: pypa/cibuildwheel@1828c10ab37f080699c7b81cea34097c684a7074  # v4.2.0
+        with:
+          output-dir: wheelhouse/
+          only: ${{ matrix.python }}-manylinux_riscv64
+        env:
+          CIBW_MANYLINUX_RISCV64_IMAGE: ${{ env.MANYLINUX_RISCV64_IMAGE }}
+          # No pyproject.toml, so the build env has neither Cython (needed to
+          # compile src/Stemmer.pyx) nor setuptools (cp312+ images don't bundle it).
+          CIBW_BEFORE_BUILD: pip install Cython setuptools
+          CIBW_BUILD_FRONTEND: "pip; args: --no-build-isolation"
+          CIBW_TEST_REQUIRES: pytest
+          # runtests.py's docs/quickstart.txt doctest is stale for libstemmer_c 3.1.0's
+          # added algorithms (arabic added czech/persian/polish/sesotho); fixed upstream
+          # on main post-v3.1.0 but not yet released, and never caught by upstream's own
+          # CI (its `\`-continued run: block never actually invokes runtests.py/nosetests).
+          CIBW_TEST_COMMAND: >-
+            python -c "import Stemmer; assert Stemmer.__file__.endswith('.so'), Stemmer.__file__"
+            && python -m pytest {project}/tests -v
+
+      - uses: actions/upload-artifact@043fb46d1a93c77aae656e7c1c64a875d1fc6a0a  # v7.0.1
+        with:
+          name: pystemmer-${{ env.PYSTEMMER_VERSION }}-${{ matrix.python }}-manylinux_riscv64
+          path: wheelhouse/*.whl
+          if-no-files-found: error
+
+  publish:
+    name: Publish pystemmer ${{ inputs.version || '3.1.0' }}
+    needs: [setup, build_wheels]
+    permissions:
+      contents: write
+      pull-requests: write
+    uses: $/.github/workflows/_publish-wheel.yml
+    with:
+      artifact-pattern: pystemmer-${{ inputs.version || '3.1.0' }}-*-manylinux_riscv64