diff --git a/tests/conftest.py b/tests/conftest.py
index b4ec0f88..b54abec4 100644
--- a/tests/conftest.py
+++ b/tests/conftest.py
@@ -1,3 +1,7 @@
+import importlib
+
+from unittest import mock
+
 import pytest
 
 
@@ -16,3 +20,24 @@ def isolate_solaar_configuration(tmp_path, monkeypatch):
     monkeypatch.setattr(configuration, "_yaml_file_path", str(tmp_path / "config.yaml"))
     monkeypatch.setattr(configuration, "_json_file_path", str(tmp_path / "config.json"))
     monkeypatch.setattr(configuration, "_config", [])
+
+
+@pytest.fixture(autouse=True)
+def mock_desktop_notifications(monkeypatch):
+    """Swap the libnotify backend for a mock in both desktop_notifications
+    modules. Tests still exercise the real init/alert/show code paths, but
+    Notification.show() never reaches the daemon — without this the suite
+    raises real 'MockDevice' / 'unknown' notifications on every run.
+
+    Returns the Notify mock so notification tests can assert against it."""
+    notify = mock.MagicMock(name="Notify")
+    notify.is_initted.return_value = True
+    notify.init.return_value = True
+    for modname in ("solaar.ui.desktop_notifications", "logitech_receiver.desktop_notifications"):
+        try:
+            module = importlib.import_module(modname)
+        except Exception:
+            continue
+        monkeypatch.setattr(module, "Notify", notify, raising=False)
+        monkeypatch.setattr(module, "_notifications", {}, raising=False)
+    return notify
diff --git a/tests/logitech_receiver/test_desktop_notifications.py b/tests/logitech_receiver/test_desktop_notifications.py
index 22905862..176cb205 100644
--- a/tests/logitech_receiver/test_desktop_notifications.py
+++ b/tests/logitech_receiver/test_desktop_notifications.py
@@ -2,7 +2,9 @@ from unittest import mock
 
 from logitech_receiver import desktop_notifications
 
-# depends on external environment, so make some tests dependent on availability
+# The mock_desktop_notifications autouse fixture (tests/conftest.py) swaps the
+# libnotify backend for a mock, so these exercise the real code paths without
+# raising real desktop notifications.
 
 
 def test_init():
@@ -22,8 +24,11 @@ class MockDevice(mock.Mock):
         return True
 
 
-def test_show():
-    dev = MockDevice()
-    reason = "unknown"
-    result = desktop_notifications.show(dev, reason)
-    assert result is not None if desktop_notifications.available else result is None
+def test_show(mock_desktop_notifications):
+    result = desktop_notifications.show(MockDevice(), "unknown")
+
+    if desktop_notifications.available:
+        assert result is not None
+        mock_desktop_notifications.Notification.return_value.show.assert_called()
+    else:
+        assert result is None
diff --git a/tests/solaar/ui/test_desktop_notifications.py b/tests/solaar/ui/test_desktop_notifications.py
index c3c16f30..72000ccc 100644
--- a/tests/solaar/ui/test_desktop_notifications.py
+++ b/tests/solaar/ui/test_desktop_notifications.py
@@ -2,7 +2,9 @@ from unittest import mock
 
 from solaar.ui import desktop_notifications
 
-# depends on external environment, so make some tests dependent on availability
+# The mock_desktop_notifications autouse fixture (tests/conftest.py) swaps the
+# libnotify backend for a mock, so these exercise the real code paths without
+# raising real desktop notifications.
 
 
 def test_init():
@@ -15,9 +17,11 @@ def test_uninit():
     assert desktop_notifications.uninit() is None
 
 
-def test_alert():
-    reason = "unknown"
-    assert desktop_notifications.alert(reason) is None
+def test_alert(mock_desktop_notifications):
+    assert desktop_notifications.alert("unknown") is None
+
+    if desktop_notifications.available:
+        mock_desktop_notifications.Notification.return_value.show.assert_called()
 
 
 class MockDevice(mock.Mock):
@@ -27,13 +31,11 @@ class MockDevice(mock.Mock):
         return True
 
 
-def test_show():
-    dev = MockDevice()
-    reason = "unknown"
-    available = desktop_notifications.init()
+def test_show(mock_desktop_notifications):
+    result = desktop_notifications.show(MockDevice(), "unknown")
 
-    result = desktop_notifications.show(dev, reason)
-    if available:
+    if desktop_notifications.available:
         assert result is not None
+        mock_desktop_notifications.Notification.return_value.show.assert_called()
     else:
         assert result is None