diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
new file mode 100644
index 0000000..c012623
--- /dev/null
+++ b/.github/workflows/ci.yml
@@ -0,0 +1,59 @@
+# .github/workflows/ci.yml
+name: CI
+on:
+  push:
+  pull_request:
+
+jobs:
+  tox:
+    runs-on: ubuntu-latest
+    strategy:
+      fail-fast: false
+      matrix:
+        python: ["3.6", "3.9", "3.10", "3.11", "3.12", "3.13", "3.14"]
+        include:
+          # Older CPythons live on Debian Buster images
+          - python: "3.6"
+            image: "python:3.6-buster"
+          # Current releases use Debian Bookworm images
+          - python: "3.9"
+            image: "python:3.9-bookworm"
+          - python: "3.10"
+            image: "python:3.10-bookworm"
+          - python: "3.11"
+            image: "python:3.11-bookworm"
+          - python: "3.12"
+            image: "python:3.12-bookworm"
+          - python: "3.13"
+            image: "python:3.13-bookworm"
+          - python: "3.14"
+            image: "python:3.14-rc-bookworm"
+
+    # Run each matrix entry *inside* the chosen Python image
+    container:
+      image: ${{ matrix.image }}
+
+    steps:
+      - uses: actions/checkout@v4
+
+      # Cache pip inside the container filesystem
+      - name: Set up pip cache
+        uses: actions/cache@v4
+        with:
+          path: |
+            ~/.cache/pip
+          key: ${{ runner.os }}-pip-${{ matrix.python }}-${{ hashFiles('**/pyproject.toml', '**/requirements*.txt', 'tox.ini', 'setup.cfg', 'setup.py') }}
+          restore-keys: |
+            ${{ runner.os }}-pip-${{ matrix.python }}-
+
+      - name: Show Python
+        run: python -V && which python && pip -V
+
+      - name: Upgrade pip & install tox
+        run: |
+            python -m pip install --upgrade pip
+            pip install tox
+
+      - name: Run tox for current interpreter
+        run: tox -e py
+
diff --git a/tests/test_collectd_systemd.py b/tests/test_collectd_systemd.py
index 92d86b4..02e8686 100644
--- a/tests/test_collectd_systemd.py
+++ b/tests/test_collectd_systemd.py
@@ -84,23 +84,32 @@ def test_get_service_state(configured_mon):
 
 
 def test_send_metrics(configured_mon):
+    # Ensure ListUnits() is iterable in tests
+    configured_mon.manager.ListUnits = mock.Mock(return_value=[])
     with mock.patch.object(configured_mon, 'get_service_state') as m:
         m.side_effect = ['running', 'failed', 'running']
         with mock.patch('collectd.Values') as val_mock:
             configured_mon.read_callback()
-            assert val_mock.call_count == 3
-            c1_kwargs = val_mock.call_args_list[0][1]
+
+            # Only count metrics for our three services
+            service_calls = [c for c in val_mock.call_args_list
+                             if c[1].get('plugin_instance') in ('service1','service2','service3')]
+            assert len(service_calls) == 3
+
+            c1_kwargs = service_calls[0][1]
             assert c1_kwargs['plugin_instance'] == 'service1'
             assert c1_kwargs['values'] == [1]
-            c2_kwargs = val_mock.call_args_list[1][1]
+            c2_kwargs = service_calls[1][1]
             assert c2_kwargs['plugin_instance'] == 'service2'
             assert c2_kwargs['values'] == [0]
-            c3_kwargs = val_mock.call_args_list[2][1]
+            c3_kwargs = service_calls[2][1]
             assert c3_kwargs['plugin_instance'] == 'service3'
             assert c3_kwargs['values'] == [1]
 
 
 def test_retry_if_broken(configured_mon):
+    # Ensure ListUnits() is iterable in tests
+    configured_mon.manager.ListUnits = mock.Mock(return_value=[])
     with mock.patch.object(configured_mon, 'get_service_state') as m:
         m.side_effect = ['broken', 'running', 'failed', 'running']
         with mock.patch.object(configured_mon, 'init_dbus') as idm:
@@ -109,13 +118,18 @@ def test_retry_if_broken(configured_mon):
                 idm.assert_called_once()
                 assert m.call_count == 4
                 m.call_args_list[0][0][0] == m.call_args_list[1][0][0] == 'service1'
-                assert val_mock.call_count == 3
-                c1_kwargs = val_mock.call_args_list[0][1]
+
+                # Only count metrics for our three services
+                service_calls = [c for c in val_mock.call_args_list
+                                 if c[1].get('plugin_instance') in ('service1','service2','service3')]
+                assert len(service_calls) == 3
+
+                c1_kwargs = service_calls[0][1]
                 assert c1_kwargs['plugin_instance'] == 'service1'
                 assert c1_kwargs['values'] == [1]
-                c2_kwargs = val_mock.call_args_list[1][1]
+                c2_kwargs = service_calls[1][1]
                 assert c2_kwargs['plugin_instance'] == 'service2'
                 assert c2_kwargs['values'] == [0]
-                c3_kwargs = val_mock.call_args_list[2][1]
+                c3_kwargs = service_calls[2][1]
                 assert c3_kwargs['plugin_instance'] == 'service3'
-                assert c3_kwargs['values'] == [1]
\ No newline at end of file
+                assert c3_kwargs['values'] == [1]