diff --git a/.github/workflows/smoke.yml b/.github/workflows/smoke.yml
index 74cd42ad0..44f1ac833 100644
--- a/.github/workflows/smoke.yml
+++ b/.github/workflows/smoke.yml
@@ -43,15 +43,29 @@ jobs:
       fail-fast: false
       matrix:
         config:
-          - {os: ubuntu-24.04, python: "3.14", ffmpeg: "9.0.1", extras: true}
-          - {os: ubuntu-24.04, python: "3.12", ffmpeg: "8.1.2"}
-          - {os: ubuntu-24.04, python: "3.13", ffmpeg: "9.0.1"}
-          - {os: macos-14, python: "3.12", ffmpeg: "8.1.2"}
-          - {os: macos-14, python: "3.14", ffmpeg: "9.0.1"}
+          - {os: ubuntu-24.04, python: "3.14", ffmpeg: "9.0.1", ffmpeg_config: ffmpeg-latest.json, extras: true}
+          - {os: ubuntu-24.04, python: "3.12", ffmpeg: "8.1.2", ffmpeg_config: ffmpeg-8.1.json}
+          - {os: ubuntu-24.04, python: "3.13", ffmpeg: "9.0.1", ffmpeg_config: ffmpeg-latest.json}
+          - {os: ubuntu-24.04-riscv, python: "3.14", ffmpeg: "9.0.1", ffmpeg_config: ffmpeg-latest.json, extras: true}
+          - {os: ubuntu-24.04-riscv, python: "3.12", ffmpeg: "8.1.2", ffmpeg_config: ffmpeg-8.1.json}
+          - {os: ubuntu-24.04-riscv, python: "3.13", ffmpeg: "9.0.1", ffmpeg_config: ffmpeg-latest.json}
+          - {os: macos-14, python: "3.12", ffmpeg: "8.1.2", ffmpeg_config: ffmpeg-8.1.json}
+          - {os: macos-14, python: "3.14", ffmpeg: "9.0.1", ffmpeg_config: ffmpeg-latest.json}
 
     env:
       PYAV_PYTHON: python${{ matrix.config.python }}
       PYAV_LIBRARY: ffmpeg-${{ matrix.config.ffmpeg }}
+      # riscv64 wheels (e.g. Pillow) are often missing on PyPI; RISE mirrors
+      # prebuilt wheels for it so uv doesn't have to build them from source.
+      # unsafe-best-match is needed so uv still falls back to PyPI for
+      # packages/versions RISE doesn't happen to carry.
+      UV_INDEX: ${{ matrix.config.os == 'ubuntu-24.04-riscv' && 'https://pypi.riseproject.dev/simple/' || '' }}
+      UV_INDEX_STRATEGY: ${{ matrix.config.os == 'ubuntu-24.04-riscv' && 'unsafe-best-match' || 'first-index' }}
+      # pyav-ffmpeg's vendor packages bake prefix=/tmp/vendor into their .pc
+      # files (not relocatable), so they must be extracted there verbatim.
+      PKG_CONFIG_PATH: /tmp/vendor/lib/pkgconfig
+      LD_LIBRARY_PATH: /tmp/vendor/lib
+      DYLD_LIBRARY_PATH: /tmp/vendor/lib
 
     steps:
     - uses: actions/checkout@v7
@@ -64,33 +78,18 @@ jobs:
         python-version: ${{ matrix.config.python }}
 
     - name: OS Packages
+      if: runner.os == 'Linux'
       run: |
-        case ${{ matrix.config.os }} in
-          ubuntu-24.04)
-            sudo apt-get update
-            sudo apt-get install \
-              autoconf \
-              automake \
-              build-essential \
-              cmake \
-              libtool \
-              libx264-dev \
-              nasm \
-              pkg-config \
-              zlib1g-dev
-            if [[ "${{ matrix.config.extras }}" ]]; then
-              sudo apt-get install doxygen
-            fi
-            ;;
-          macos-14)
-            brew install automake libtool opus x264
-            ;;
-        esac
-
-    - name: Pip and FFmpeg
+        sudo apt-get update
+        sudo apt-get install -y build-essential cmake pkg-config zlib1g-dev libxcb-shape0
+        if [[ "${{ matrix.config.extras }}" ]]; then
+          sudo apt-get install -y doxygen
+        fi
+
+    - name: FFmpeg
       run: |
         . scripts/activate.sh ffmpeg-${{ matrix.config.ffmpeg }}
-        scripts/build-deps
+        python scripts/fetch-vendor.py --config-file scripts/${{ matrix.config.ffmpeg_config }} /tmp/vendor
 
     - name: Build
       run: |
diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
index eb4b4c294..7189a0566 100644
--- a/.github/workflows/tests.yml
+++ b/.github/workflows/tests.yml
@@ -33,6 +33,8 @@ jobs:
             arch: arm64
           - os: macos-15-intel
             arch: x86_64
+          - os: ubuntu-24.04-riscv
+            arch: riscv64
           - os: ubuntu-24.04-arm
             arch: aarch64
           - os: ubuntu-24.04
@@ -61,7 +63,10 @@ jobs:
           CIBW_BEFORE_BUILD: python scripts/fetch-vendor.py --config-file scripts/ffmpeg-latest.json /tmp/vendor
           CIBW_BEFORE_BUILD_MACOS: python scripts/fetch-vendor.py --config-file scripts/ffmpeg-latest.json /tmp/vendor
           CIBW_BEFORE_BUILD_WINDOWS: python scripts\fetch-vendor.py --config-file scripts\ffmpeg-latest.json C:\cibw\vendor
-          CIBW_ENVIRONMENT_LINUX: LD_LIBRARY_PATH=/tmp/vendor/lib:$LD_LIBRARY_PATH PKG_CONFIG_PATH=/tmp/vendor/lib/pkgconfig
+          # riscv64 wheels (e.g. numpy, for CIBW_TEST_REQUIRES) are often missing on
+          # PyPI; RISE mirrors prebuilt wheels for it. unsafe-best-match is needed so
+          # uv still falls back to PyPI for packages/versions RISE doesn't carry.
+          CIBW_ENVIRONMENT_LINUX: LD_LIBRARY_PATH=/tmp/vendor/lib:$LD_LIBRARY_PATH PKG_CONFIG_PATH=/tmp/vendor/lib/pkgconfig${{ matrix.arch == 'riscv64' && ' UV_INDEX=https://pypi.riseproject.dev/simple/ UV_INDEX_STRATEGY=unsafe-best-match' || '' }}
           CIBW_ENVIRONMENT_MACOS: PKG_CONFIG_PATH=/tmp/vendor/lib/pkgconfig LDFLAGS=-headerpad_max_install_names
           CIBW_ENVIRONMENT_WINDOWS: INCLUDE=C:\\cibw\\vendor\\include LIB=C:\\cibw\\vendor\\lib PYAV_SKIP_TESTS=unicode_filename
           CIBW_REPAIR_WHEEL_COMMAND_WINDOWS: delvewheel repair --add-path C:\cibw\vendor\bin -w {dest_dir} {wheel}