diff --git a/.github/workflows/test_action.yml b/.github/workflows/test_action.yml
new file mode 100644
index 00000000..00240bab
--- /dev/null
+++ b/.github/workflows/test_action.yml
@@ -0,0 +1,24 @@
+name: test-action
+
+on:
+  pull_request:
+  workflow_dispatch:
+
+jobs:
+  test-action:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      # Build your Docker image.
+
+      - name: Run QUIC Interop tests
+        uses: ./
+        with:
+          name: 'neqo-latest'
+          # Replace with the name of the freshly-build local docker image.
+          image: 'ghcr.io/mozilla/neqo-qns:latest'
+          url: https://github.com/mozilla/neqo
+          test: handshake
+          client: neqo-latest,quic-go,ngtcp2,neqo,msquic
+          server: neqo-latest,quic-go,ngtcp2,neqo,msquic
diff --git a/.github/workflows/test_action_comment.yml b/.github/workflows/test_action_comment.yml
new file mode 100644
index 00000000..547c9b56
--- /dev/null
+++ b/.github/workflows/test_action_comment.yml
@@ -0,0 +1,56 @@
+# Post test results as pull request comment.
+#
+# This is done as a separate workflow as it requires write permissions. The
+# tests itself might run off of a fork, i.e. an untrusted environment and should
+# thus not be granted write permissions.
+
+name: test-action-comment
+
+on:
+  workflow_run:
+    workflows: ["test-action"]
+    types:
+      - completed
+
+jobs:
+  comment:
+    permissions:
+      pull-requests: write
+    runs-on: ubuntu-latest
+    if: >
+      github.event.workflow_run.event == 'pull_request' &&
+      github.event.workflow_run.conclusion == 'failure'
+    steps:
+      - name: Download comment-data
+        uses: actions/download-artifact@v4
+        with:
+          run-id: ${{ github.event.workflow_run.id }}
+          name: comment-data
+          github-token: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: Format GitHub comment
+        run: |
+          pwd
+          ls -la
+          echo '[**QUIC Interop Runner**](https://github.com/quic-interop/quic-interop-runner)' >> comment
+          echo '' >> comment
+          echo '```' >> comment
+          cat summary >> comment
+          echo '```' >> comment
+          echo '' >> comment
+          echo 'Download artifacts [here](' >> comment
+          cat logs-url >> comment
+          echo ').' >> comment
+        shell: bash
+
+      - name: Read PR Number
+        id: pr-number
+        run: echo "::set-output name=number::$(cat pr-number)"
+        shell: bash
+
+      - name: Comment PR
+        uses: thollander/actions-comment-pull-request@v2
+        with:
+          filePath: comment
+          pr_number: ${{ steps.pr-number.outputs.number }}
+          comment_tag: quic-network-simulator-comment
diff --git a/action.yml b/action.yml
new file mode 100644
index 00000000..34a1ce46
--- /dev/null
+++ b/action.yml
@@ -0,0 +1,113 @@
+name: 'QUIC Interop Runner Action'
+description: 'Run the QUIC Interop Runner tests.'
+author: 'mxinden'
+
+inputs:
+  name:
+    description: 'Name of the QUIC implementation'
+    required: true
+  image:
+    description: 'Docker image to be tested. Needs to reside either locally, or on some registry.'
+    required: true
+  url:
+    description: 'URL of the QUIC implementation'
+    required: true
+  role:
+    description: 'client/server/both'
+    required: false
+    default: 'both'
+  client:
+    description: 'client implementations (comma-separated)'
+    required: false
+    default: ''
+  server:
+    description: 'server implementations (comma-separated)'
+    required: false
+    default: ''
+  test:
+    description: 'test cases (comma-separatated)'
+    required: false
+    default: ''
+
+runs:
+  using: "composite"
+  steps:
+    # TODO: Update repository and ref
+    - name: Checkout quic-interop/quic-interop-runner repository
+      uses: actions/checkout@v4
+      with:
+        repository: 'mxinden/quic-interop-runner'
+        ref: 'action'
+        path: 'quic-interop-runner'
+
+    - name: Enable IPv6 support
+      run: sudo modprobe ip6table_filter
+      shell: bash
+
+    - name: Install dependencies
+      run: |
+        sudo add-apt-repository ppa:wireshark-dev/stable
+        sudo apt-get update
+        sudo apt-get install -y wireshark tshark jq
+      shell: bash
+
+    - uses: actions/setup-python@v5
+      with:
+        python-version: 3.8
+        cache: 'pip'
+        cache-dependency-path: 'quic-interop-runner/requirements.txt'
+
+    - name: Install Python packages
+      run: |
+        cd quic-interop-runner
+        pip install -U pip
+        pip install -r requirements.txt
+      shell: bash
+
+    - name: Run tests
+      id: test-run
+      run: |
+        cd quic-interop-runner
+        jq --arg key "${{ inputs.name }}" --argjson newEntry '{"image": "${{ inputs.image }}", "url": "${{ inputs.url }}", "role": "${{ inputs.role }}"}' '.[$key] = $newEntry' implementations.json > temp.$$ && mv temp.$$ implementations.json
+        cat implementations.json
+        ARGS="--log-dir logs --markdown --must-include ${{ inputs.name }}"
+        if [ -n "${{ inputs.client }}" ]; then
+          ARGS="$ARGS --client ${{ inputs.client }}"
+        fi
+        if [ -n "${{ inputs.server }}" ]; then
+          ARGS="$ARGS --server ${{ inputs.server }}"
+        fi
+        if [ -n "${{ inputs.test }}" ]; then
+          ARGS="$ARGS --test ${{ inputs.test }}"
+        fi
+        python run.py $ARGS 2>&1 | tee summary
+      shell: bash
+
+    - uses: actions/upload-artifact@v4
+      id: artifact-upload-step
+      if: always()
+      with:
+        name: logs
+        path: quic-interop-runner/logs
+
+    # This action might be running off of a fork and would thus not have write
+    # permissions on the origin repository. In order to allow a separate
+    # priviledged action to post a comment on a pull request, upload the
+    # necessary metadata.
+    - name: store comment-data
+      shell: bash
+      if: github.event_name == 'pull_request'
+      env:
+        PULL_REQUEST_NUMBER: ${{ github.event.number }}
+      run: |
+        mkdir comment-data
+        cat quic-interop-runner/summary | awk '/^\|:--/{flag=1} flag' >> comment-data/summary
+        echo $PULL_REQUEST_NUMBER > comment-data/pr-number
+        echo '${{ steps.artifact-upload-step.outputs.artifact-url }}' > comment-data/logs-url
+
+    - name: Upload comment data
+      uses: actions/upload-artifact@v4
+      if: github.event_name == 'pull_request'
+      with:
+        name: comment-data
+        path: ./comment-data
diff --git a/interop.py b/interop.py
index 0a7126d7..8f2769b8 100644
--- a/interop.py
+++ b/interop.py
@@ -240,7 +240,7 @@ def get_letters(result):
                         results.append(colored(measurement.abbreviation(), "grey"))
                     elif res.result == TestResult.FAILED:
                         results.append(colored(measurement.abbreviation(), "red"))
-                row[server] += "\n".join(results)
+                row[server] = "\n".join(results)
             t.field_names = [""] + [column for column, _ in columns.items()]
             for client, results in rows.items():
                 row = [client]