diff --git a/src/seedpass_gui/app.py b/src/seedpass_gui/app.py
index 0b06153d..414ec3ed 100644
--- a/src/seedpass_gui/app.py
+++ b/src/seedpass_gui/app.py
@@ -187,7 +187,11 @@ class MainWindow(toga.Window):
         self.status.text = f"Last sync: {self.last_sync}"
 
     def vault_locked(self, *args: object, **kwargs: object) -> None:
-        self.close()
+        try:
+            self.close()
+        except ValueError:
+            # Handle case where window is already detached (e.g. in tests)
+            pass
         self.controller.main_window = None
         self.controller.lock_window.show()
 
@@ -391,7 +395,7 @@ class TotpViewerWindow(toga.Window):
             self.refresh_codes()
             await asyncio.sleep(1)
 
-    def refresh_codes(self) -> None:
+    def refresh_codes(self, *args: object, **kwargs: object) -> None:
         self.table.data = []
         for idx, label, *_rest in self.entries.list_entries(
             filter_kinds=[EntryType.TOTP.value]
diff --git a/src/tests/conftest.py b/src/tests/conftest.py
index 00a179ee..7696800f 100644
--- a/src/tests/conftest.py
+++ b/src/tests/conftest.py
@@ -30,9 +30,15 @@ from seedpass.core.manager import EncryptionMode, PasswordManager
 from seedpass.core.encryption import EncryptionManager as EncMgr
 from seedpass.core.pubsub import bus
 
+# Robust check for trio availability
+try:
+    import trio
+    has_trio = True
+except ImportError:
+    has_trio = False
 
 @pytest.fixture(
-    params=["asyncio"] + (["trio"] if importlib.util.find_spec("trio") else [])
+    params=["asyncio"] + (["trio"] if has_trio else [])
 )
 def anyio_backend(request):
     return request.param
diff --git a/src/tests/test_gui_features.py b/src/tests/test_gui_features.py
index f7f8b63c..7beef10c 100644
--- a/src/tests/test_gui_features.py
+++ b/src/tests/test_gui_features.py
@@ -108,8 +108,12 @@ def test_totp_viewer_refresh_on_sync(monkeypatch):
     viewer = seedpass_gui.app.TotpViewerWindow(ctrl, entries)
     bus.subscribe("sync_finished", viewer.refresh_codes)
 
-    # Table rows are Row objects with attribute access
-    assert viewer.table.data[0].code == "111111"
-    entries.code = "222222"
-    bus.publish("sync_finished")
-    assert viewer.table.data[0].code == "222222"
+    try:
+        # Table rows are Row objects with attribute access
+        assert viewer.table.data[0].code == "111111"
+        entries.code = "222222"
+        bus.publish("sync_finished")
+        assert viewer.table.data[0].code == "222222"
+    finally:
+        # Ensure we unsubscribe to prevent test pollution
+        bus.unsubscribe("sync_finished", viewer.refresh_codes)