diff --git a/mantidimaging/gui/windows/live_viewer/view.py b/mantidimaging/gui/windows/live_viewer/view.py
index e9c92b3aa21..54a13d6a0b9 100644
--- a/mantidimaging/gui/windows/live_viewer/view.py
+++ b/mantidimaging/gui/windows/live_viewer/view.py
@@ -26,7 +26,7 @@ class LiveViewerWindowView(BaseMainWindowView):
     imageLayout: QVBoxLayout
 
     def __init__(self, main_window: 'MainWindowView', live_dir_path: Path) -> None:
-        super().__init__(main_window, 'gui/ui/live_viewer_window.ui')
+        super().__init__(None, 'gui/ui/live_viewer_window.ui')
         self.setWindowTitle("Mantid Imaging - Live Viewer")
         self.main_window = main_window
         self.path = live_dir_path
diff --git a/mantidimaging/gui/windows/main/view.py b/mantidimaging/gui/windows/main/view.py
index 69386b15aa7..3d071b2d22d 100644
--- a/mantidimaging/gui/windows/main/view.py
+++ b/mantidimaging/gui/windows/main/view.py
@@ -490,6 +490,15 @@ def closeEvent(self, event):
         if should_close:
             # Pass close event to parent
             super().closeEvent(event)
+            # Close additional windows which do not have the MainWindow as parent
+            if self.recon:
+                self.recon.close()
+            if self.live_viewer:
+                self.live_viewer.close()
+            if self.spectrum_viewer:
+                self.spectrum_viewer.close()
+            if self.filters:
+                self.filters.close()
 
         else:
             # Ignore the close event, keeping window open
diff --git a/mantidimaging/gui/windows/operations/view.py b/mantidimaging/gui/windows/operations/view.py
index 2e06e11d0cb..bda6af264f1 100644
--- a/mantidimaging/gui/windows/operations/view.py
+++ b/mantidimaging/gui/windows/operations/view.py
@@ -59,7 +59,7 @@ class FiltersWindowView(BaseMainWindowView):
     filterSelector: QComboBox
 
     def __init__(self, main_window: 'MainWindowView'):
-        super().__init__(main_window, 'gui/ui/filters_window.ui')
+        super().__init__(None, 'gui/ui/filters_window.ui')
 
         self.main_window = main_window
         self.presenter = FiltersWindowPresenter(self, main_window)
diff --git a/mantidimaging/gui/windows/recon/view.py b/mantidimaging/gui/windows/recon/view.py
index 7ae88f5b5b9..038d466d04b 100644
--- a/mantidimaging/gui/windows/recon/view.py
+++ b/mantidimaging/gui/windows/recon/view.py
@@ -83,7 +83,7 @@ class ReconstructWindowView(BaseMainWindowView):
     stackSelector: DatasetSelectorWidgetView
 
     def __init__(self, main_window: 'MainWindowView'):
-        super().__init__(main_window, 'gui/ui/recon_window.ui')
+        super().__init__(None, 'gui/ui/recon_window.ui')
 
         self.main_window = main_window
         self.presenter = ReconstructWindowPresenter(self, main_window)
diff --git a/mantidimaging/gui/windows/spectrum_viewer/view.py b/mantidimaging/gui/windows/spectrum_viewer/view.py
index cc34f436dc3..d01b2383684 100644
--- a/mantidimaging/gui/windows/spectrum_viewer/view.py
+++ b/mantidimaging/gui/windows/spectrum_viewer/view.py
@@ -38,7 +38,7 @@ class SpectrumViewerWindowView(BaseMainWindowView):
     normalise_error_issue: str = ""
 
     def __init__(self, main_window: 'MainWindowView'):
-        super().__init__(main_window, 'gui/ui/spectrum_viewer.ui')
+        super().__init__(None, 'gui/ui/spectrum_viewer.ui')
 
         self.main_window = main_window
 
diff --git a/mantidimaging/gui/windows/wizard/view.py b/mantidimaging/gui/windows/wizard/view.py
index 302ccfa2ea4..f131337667d 100644
--- a/mantidimaging/gui/windows/wizard/view.py
+++ b/mantidimaging/gui/windows/wizard/view.py
@@ -15,7 +15,7 @@
 class WizardStage(QWidget):
 
     def __init__(self, name, parent: QWidget = None) -> None:
-        super().__init__(parent)
+        super().__init__(None)
 
         self.layout = QVBoxLayout(self)
         self.title_label = QLabel("Stage: " + name)
@@ -34,7 +34,7 @@ def handle_stack_change(self, stack_history: Optional[dict]) -> None:
 class WizardStep(QWidget):
 
     def __init__(self, step: dict, wizard: WizardView, parent: QWidget = None) -> None:
-        super().__init__(parent)
+        super().__init__(None)
 
         self.wizard_view = wizard