diff --git a/.github/workflows/python-app.yml b/.github/workflows/python-app.yml
new file mode 100644
index 0000000..1168bd9
--- /dev/null
+++ b/.github/workflows/python-app.yml
@@ -0,0 +1,39 @@
+# This workflow will install Python dependencies, run tests and lint with a single version of Python
+# For more information see: https://docs.github.com/en/actions/automating-builds-and-tests/building-and-testing-python
+
+name: Python application
+
+on:
+  push:
+    branches: [ "main" ]
+  pull_request:
+    branches: [ "main" ]
+
+permissions:
+  contents: read
+
+jobs:
+  build:
+
+    runs-on: ubuntu-latest
+
+    steps:
+    - uses: actions/checkout@v4
+    - name: Set up Python 3.10
+      uses: actions/setup-python@v3
+      with:
+        python-version: "3.10"
+    - name: Install dependencies
+      run: |
+        python -m pip install --upgrade pip
+        pip install flake8 pytest
+        if [ -f requirements.txt ]; then pip install -r requirements.txt; fi
+    - name: Lint with flake8
+      run: |
+        # stop the build if there are Python syntax errors or undefined names
+        flake8 . --count --select=E9,F63,F7,F82 --show-source --statistics
+        # exit-zero treats all errors as warnings. The GitHub editor is 127 chars wide
+        flake8 . --count --exit-zero --max-complexity=10 --max-line-length=127 --statistics
+    - name: Test with pytest
+      run: |
+        pytest
diff --git a/plugins/autoresponder/plugin.py b/plugins/autoresponder/plugin.py
index e135f9c..f4884ff 100644
--- a/plugins/autoresponder/plugin.py
+++ b/plugins/autoresponder/plugin.py
@@ -60,10 +60,12 @@ def _build_message_payload(mention: str, body: str, *, prepend_mention: bool = F
     if normalized_body:
         if requires_prepend:
             block_text = f"{mention}\n\n{normalized_body}"
-            fallback_text = f"{mention} {normalized_body.replace('\n', ' ')}"
+            normalized_single_line = normalized_body.replace('\n', ' ')
+            fallback_text = f"{mention} {normalized_single_line}"
         else:
             block_text = normalized_body
-            fallback_text = normalized_body.replace('\n', ' ')
+            normalized_single_line = normalized_body.replace('\n', ' ')
+            fallback_text = normalized_single_line
     else:
         block_text = mention
         fallback_text = mention