diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
index dedc189..4419c1e 100644
--- a/.github/workflows/tests.yml
+++ b/.github/workflows/tests.yml
@@ -42,6 +42,8 @@ jobs:
             pytest_args: -m "not integration" -v --cov --cov-append --cov-report=xml
           - os: windows-latest
             pytest_args: -m "not integration" -v --cov --cov-append --cov-report=xml
+    env:
+      COVERAGE_FILE: .coverage.${{ matrix.os }}
     steps:
       - uses: actions/checkout@v4
         with:
@@ -52,6 +54,48 @@ jobs:
         run: uv sync --locked --all-extras --dev
       - name: Run tests
         run: uv run tox -- ${{ matrix.pytest_args }}
+      - name: debug coverage output
+        shell: bash
+        run: |
+          echo "pwd=$(pwd)"
+          echo "GITHUB_WORKSPACE=$GITHUB_WORKSPACE"
+          echo "COVERAGE_FILE=$COVERAGE_FILE"
+          echo "ls in pwd:"
+          ls -la
+          echo "ls in workspace:"
+          ls -la "$GITHUB_WORKSPACE"
+          echo "find coverage under workspace:"
+          find "$GITHUB_WORKSPACE" -maxdepth 5 -name ".coverage*" -print
+          echo "find coverage under pwd:"
+          find "$(pwd)" -maxdepth 5 -name ".coverage*" -print
+      - name: Upload coverage artifact
+        uses: actions/upload-artifact@v4
+        with:
+          name: coverage-${{ matrix.os }}
+          path: ${{ github.workspace }}/${{ env.COVERAGE_FILE }}
+          if-no-files-found: error
+          include-hidden-files: true
+  coverage:
+    name: Upload Coverage
+    runs-on: ubuntu-latest
+    needs: tests
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
+      - name: Install uv
+        uses: astral-sh/setup-uv@v6
+      - name: Install the project
+        run: uv sync --locked --all-extras --dev
+      - name: Download coverage artifacts
+        uses: actions/download-artifact@v4
+        with:
+          path: coverage_artifacts
+      - name: Combine coverage
+        run: |
+          uv run coverage combine --ignore-errors coverage_artifacts/**/.coverage.*
+          uv run coverage xml -o coverage.xml
+          uv run coverage report -m
       - name: Upload coverage reports to Codecov
         uses: codecov/codecov-action@v5
         with:
diff --git a/diff b/diff
new file mode 100644
index 0000000..a10a4db
--- /dev/null
+++ b/diff
@@ -0,0 +1,47 @@
+diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
+index dedc189..b6fee54 100644
+--- a/.github/workflows/tests.yml
++++ b/.github/workflows/tests.yml
+@@ -42,6 +42,8 @@ jobs:
+             pytest_args: -m "not integration" -v --cov --cov-append --cov-report=xml
+           - os: windows-latest
+             pytest_args: -m "not integration" -v --cov --cov-append --cov-report=xml
++    env:
++      COVERAGE_FILE: .coverage.${{ matrix.os }}
+     steps:
+       - uses: actions/checkout@v4
+         with:
+@@ -52,6 +54,33 @@ jobs:
+         run: uv sync --locked --all-extras --dev
+       - name: Run tests
+         run: uv run tox -- ${{ matrix.pytest_args }}
++      - name: Upload coverage artifact
++        uses: actions/upload-artifact@v4
++        with:
++          name: coverage-${{ matrix.os }}
++          path: ${{ env.COVERAGE_FILE }}
++          if-no-files-found: error
++  coverage:
++    name: Combine & Upload Coverage
++    runs-on: ubuntu-latest
++    needs: tests
++    steps:
++      - uses: actions/checkout@v4
++        with:
++          fetch-depth: 0
++      - name: Install uv
++        uses: astral-sh/setup-uv@v6
++      - name: Install the project
++        run: uv sync --locked --all-extras --dev
++      - name: Download coverage artifacts
++        uses: actions/download-artifact@v4
++        with:
++          path: coverage_artifacts
++      - name: Combine coverage
++        run: |
++          uv run coverage combine coverage_artifacts/**/.coverage.*
++          uv run coverage xml -o coverage.xml
++          uv run coverage report -m
+       - name: Upload coverage reports to Codecov
+         uses: codecov/codecov-action@v5
+         with:
diff --git a/tox.ini b/tox.ini
index 7fb0861..f3270e3 100644
--- a/tox.ini
+++ b/tox.ini
@@ -13,6 +13,7 @@ env_list =
 runner = uv-venv-lock-runner
 description = run the tests with pytest
 pass_env =
+    COVERAGE_FILE
     DOCKER_HOST
     RYUK_CONTAINER_IMAGE
     RYUK_RECONNECTION_TIMEOUT