diff --git a/tests/test_mainwin.py b/tests/test_mainwin.py
index 581acd2..da58e87 100644
--- a/tests/test_mainwin.py
+++ b/tests/test_mainwin.py
@@ -116,10 +116,10 @@ class TestViewUnit(unittest.TestCase):
 
         sub = MDISubPlot("sine", sine_item.value)
         mw.mdi.add(sub)
-        sub.plot.setData = mock.MagicMock()
+        sub.plots["sine"].setData = mock.MagicMock()
 
         mw.append_data("sine", point)
-        sub.plot.setData.assert_called_once_with(*sine_item.value.data)
+        sub.plots["sine"].setData.assert_called_once_with(*sine_item.value.data)
         print(sine_item.set_alarm.call_args)
         assert sine_item.set_alarm.call_args[0][0] == False