diff --git a/tests/unit/gui/test_main_window.py b/tests/unit/gui/test_main_window.py
index 6a901043..8e79c9be 100644
--- a/tests/unit/gui/test_main_window.py
+++ b/tests/unit/gui/test_main_window.py
@@ -1,3 +1,4 @@
+from typing import cast
 from unittest.mock import MagicMock, patch
 
 import pytest
@@ -105,16 +106,18 @@ def test_main_window_init(qtbot, mock_ui_state, daq_status_factory):
             == "Manual collection stopped: detector error."
         )
 
-        # Manual unmount respects the hutch PSS gate.
+        # Manual unmount respects the hutch PSS gate. cast: win.daq is a
+        # patched-in MagicMock, but pyright sees the real DAQWorker type.
+        unmount_mock = cast(MagicMock, win.daq.unmount)
         with (
             patch.object(win, "_hutch_blocks_mount", return_value="hutch open"),
             patch("aare.gui.main_window.QMessageBox"),
         ):
             win._on_manual_unmount_requested()
-        win.daq.unmount.assert_not_called()
+        unmount_mock.assert_not_called()
         with patch.object(win, "_hutch_blocks_mount", return_value=None):
             win._on_manual_unmount_requested()
-        win.daq.unmount.assert_called_once()
+        unmount_mock.assert_called_once()
 
         # Motion watch: only the robot station switches to the combined
         # beamline view. Moving no longer does (users kept losing the sample