diff --git a/.github/workflows/build-pynng.yml b/.github/workflows/build-pynng.yml
new file mode 100644
index 000000000..80131196d
--- /dev/null
+++ b/.github/workflows/build-pynng.yml
@@ -0,0 +1,104 @@
+# SPDX-FileCopyrightText: 2026 The RISE Project
+# SPDX-License-Identifier: MIT
+---
+# Based on upstream's own wheel build:
+#   https://github.com/codypiersall/pynng/blob/v0.9.0/.github/workflows/cibuildwheel.yml
+name: Build pynng wheels (riscv64)
+
+on:
+  workflow_dispatch:
+    inputs:
+      version:
+        description: 'pynng version to build (git tag without leading v, e.g. 0.9.0)'
+        required: true
+        default: '0.9.0'
+  pull_request:
+    paths:
+      - '.github/workflows/build-pynng.yml'
+
+concurrency:
+  group: ${{ github.workflow }}-${{ inputs.version || '0.9.0' }}-${{ 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 0.9.0 there.
+  PYNNG_VERSION: ${{ inputs.version || '0.9.0' }}
+  # setup.cfg's own [build_nng]/[build_mbedtls] pins; keep in lockstep with it.
+  NNG_VERSION: v1.11
+  MBEDTLS_VERSION: v3.6.3.1
+  MANYLINUX_RISCV64_IMAGE: quay.io/pypa/manylinux_2_39_riscv64
+
+jobs:
+  setup:
+    uses: $/.github/workflows/_setup.yml
+
+  build_wheels:
+    needs: [setup]
+    name: Build pynng ${{ inputs.version || '0.9.0' }} ${{ matrix.python }}-manylinux_riscv64
+    runs-on: ubuntu-24.04-riscv
+    timeout-minutes: 90
+    strategy:
+      fail-fast: false
+      matrix:
+        python: ["cp312", "cp313", "cp314", "cp314t"]
+
+    steps:
+      - name: Checkout pynng v${{ env.PYNNG_VERSION }}
+        uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1  # v7.0.1
+        with:
+          repository: codypiersall/pynng
+          ref: v${{ env.PYNNG_VERSION }}
+          submodules: recursive
+          fetch-depth: 0
+          persist-credentials: false
+
+      - name: Checkout python-wheels
+        uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1  # v7.0.1
+        with:
+          path: python-wheels
+          persist-credentials: false
+
+      # setup.py's build_nng/build_mbedtls commands `git clone` the nng and
+      # mbedtls C libraries at build time (not submodules); their licences never
+      # land in the checkout, so fetch them straight from the pinned tags above.
+      - name: Stage the nng and mbedtls licences
+        run: |
+          curl -fsSL -o LICENSE.nng https://raw.githubusercontent.com/nanomsg/nng/${{ env.NNG_VERSION }}/LICENSE.txt
+          curl -fsSL -o LICENSE.mbedtls https://raw.githubusercontent.com/ARMmbed/mbedtls/${{ env.MBEDTLS_VERSION }}/LICENSE
+
+      - name: Patch pynng source
+        run: |
+          git apply python-wheels/patches/pynng/${{ env.PYNNG_VERSION }}/00*.patch
+
+      - uses: pypa/cibuildwheel@1828c10ab37f080699c7b81cea34097c684a7074  # v4.2.0
+        env:
+          CIBW_ARCHS: riscv64
+          # cffi has no manylinux musllinux_riscv64 wheel on our registry, so
+          # musllinux is dropped here too (accepted per the porting playbook).
+          CIBW_BUILD: ${{ matrix.python }}-manylinux_riscv64
+          CIBW_MANYLINUX_RISCV64_IMAGE: ${{ env.MANYLINUX_RISCV64_IMAGE }}
+          # cffi, needed to build and to import the extension, has no riscv64 wheel on PyPI.
+          CIBW_ENVIRONMENT: PIP_EXTRA_INDEX_URL=https://pypi.riseproject.dev/simple/
+          CIBW_TEST_REQUIRES: pytest pytest-asyncio pytest-trio trio
+          CIBW_TEST_COMMAND: >-
+            python -c "import importlib.metadata as m; l = sorted(str(p).rsplit('/', 1)[-1] for p in m.files('pynng') if str(p).rsplit('/', 1)[-1].startswith('LICENSE')); assert l == ['LICENSE.mbedtls', 'LICENSE.nng', 'LICENSE.txt'], l"
+            && pytest {project}/test
+
+      - uses: actions/upload-artifact@043fb46d1a93c77aae656e7c1c64a875d1fc6a0a  # v7.0.1
+        with:
+          name: pynng-${{ env.PYNNG_VERSION }}-${{ matrix.python }}-manylinux_riscv64
+          path: ./wheelhouse/*.whl
+          if-no-files-found: error
+
+  publish:
+    name: Publish pynng ${{ inputs.version || '0.9.0' }}
+    needs: [setup, build_wheels]
+    permissions:
+      contents: write
+      pull-requests: write
+    uses: $/.github/workflows/_publish-wheel.yml
+    with:
+      artifact-pattern: pynng-${{ inputs.version || '0.9.0' }}-*-manylinux_riscv64
diff --git a/patches/pynng/0.9.0/0001-package-the-vendored-nng-and-mbedtls-licences-with-the-wheel.patch b/patches/pynng/0.9.0/0001-package-the-vendored-nng-and-mbedtls-licences-with-the-wheel.patch
new file mode 100644
index 000000000..fb19590a1
--- /dev/null
+++ b/patches/pynng/0.9.0/0001-package-the-vendored-nng-and-mbedtls-licences-with-the-wheel.patch
@@ -0,0 +1,37 @@
+From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
+From: Ludovic Henry <git@ludovic.dev>
+Date: Mon, 7 Sep 2026 22:29:27 +0200
+Subject: [PATCH] package the vendored nng and mbedtls licences with the wheel
+
+Upstream-Status: To upstream [not yet submitted; the same gap exists in every pynng wheel on PyPI, so it needs a maintainer discussion rather than a drive-by PR]
+
+setup.py's build_nng/build_mbedtls commands clone and statically link the
+nng (MIT) and mbedtls (Apache-2.0 OR GPL-2.0-or-later) C libraries into the
+_nng extension at build time, but neither library's own repository is a
+submodule or otherwise present in the sdist/checkout, and pyproject.toml
+names only pynng's own LICENSE.txt. So every published pynng wheel
+redistributes nng and mbedtls in binary form without their licence text.
+
+Add license-files under [tool.setuptools] naming LICENSE.nng and
+LICENSE.mbedtls alongside LICENSE.txt; the build now stages those two
+files (fetched from the pinned nng/mbedtls revisions in setup.cfg) before
+invoking setuptools, so they land in the wheel's licence metadata.
+---
+ pyproject.toml | 4 ++++
+ 1 file changed, 4 insertions(+)
+
+diff --git a/pyproject.toml b/pyproject.toml
+index ba23ab7..56e4819 100644
+--- a/pyproject.toml
++++ b/pyproject.toml
+@@ -62,6 +62,10 @@ Documentation = "https://pynng.readthedocs.io/en/latest/"
+ 
+ [tool.setuptools_scm]
+ version_file = "pynng/_version.py"
++
++[tool.setuptools]
++license-files = ["LICENSE.txt", "LICENSE.nng", "LICENSE.mbedtls"]
++
+ [tool.setuptools.packages.find]
+ include = ["pynng"]
+