diff --git a/.github/workflows/build_wheels.yml b/.github/workflows/build_wheels.yml
index 20af6db..a8b9d22 100644
--- a/.github/workflows/build_wheels.yml
+++ b/.github/workflows/build_wheels.yml
@@ -247,9 +247,71 @@ jobs:
           path: ./quaddtype/wheelhouse/*.whl
           name: wheels-windows-${{ matrix.architecture }}
 
+  build_sdist:
+    name: Build SDist
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v3
+        with:
+          submodules: recursive
+
+      - name: Set up Python
+        uses: actions/setup-python@v4
+        with:
+          python-version: ">=3.11.0"
+
+      - name: Verify QuadBLAS submodule
+        run: |
+          ls -la quaddtype/numpy_quaddtype/QBLAS/
+          ls -la quaddtype/numpy_quaddtype/QBLAS/include/quadblas/
+
+      - name: Install system dependencies
+        run: |
+          sudo apt-get update -y
+          sudo apt-get install -y cmake gcc g++ make git pkg-config
+
+      - name: Install SLEEF
+        run: |
+          git clone --branch 3.8 https://github.com/shibatch/sleef.git
+          cd sleef
+          cmake -S . -B build \
+            -DSLEEF_BUILD_QUAD:BOOL=ON \
+            -DSLEEF_BUILD_SHARED_LIBS:BOOL=ON \
+            -DCMAKE_POSITION_INDEPENDENT_CODE=ON
+          cmake --build build/ --clean-first -j
+          sudo cmake --install build --prefix /usr/local
+
+      - name: Install build dependencies
+        run: |
+          python -m pip install --upgrade pip
+          python -m pip install build
+
+      - name: Build SDist
+        env:
+          CFLAGS: "-I/usr/local/include -I$(pwd)/numpy_quaddtype/QBLAS/include"
+          CXXFLAGS: "-I/usr/local/include -I$(pwd)/numpy_quaddtype/QBLAS/include -fext-numeric-literals"
+          LDFLAGS: "-L/usr/local/lib64 -L/usr/local/lib -Wl,-rpath,/usr/local/lib64 -Wl,-rpath,/usr/local/lib -fopenmp"
+          LD_LIBRARY_PATH: "/usr/local/lib64:/usr/local/lib:$LD_LIBRARY_PATH"
+          PKG_CONFIG_PATH: "/usr/local/lib64/pkgconfig:/usr/local/lib/pkgconfig:$PKG_CONFIG_PATH"
+        run: |
+          python -m build --sdist --outdir dist/
+        working-directory: ./quaddtype
+
+      - name: Upload SDist artifact
+        uses: actions/upload-artifact@v4
+        with:
+          name: sdist
+          path: ./quaddtype/dist/*.tar.gz
+
   publish_to_pypi:
     name: Publish to PyPI
-    needs: [build_wheels_linux, build_wheels_macos, build_wheels_windows]
+    needs:
+      [
+        build_wheels_linux,
+        build_wheels_macos,
+        build_wheels_windows,
+        build_sdist,
+      ]
     runs-on: ubuntu-latest
     if: startsWith(github.ref, 'refs/tags/quaddtype-v')
 
@@ -264,9 +326,9 @@ jobs:
       - name: Download all workflow run artifacts
         uses: actions/download-artifact@v4
         with:
+          pattern: "*"
           path: dist
+          merge-multiple: true
 
       - name: Publish to PyPI
         uses: pypa/gh-action-pypi-publish@release/v1
-        with:
-          packages-dir: dist/*