diff --git a/qt/app.py b/qt/app.py
index 7d9891e8..47051ea9 100644
--- a/qt/app.py
+++ b/qt/app.py
@@ -271,6 +271,9 @@ class DupeGuru(QObject):
         self.willSavePrefs.emit()
         self.prefs.save()
         self.model.save()
+        # Workaround for #857, hide() or close().
+        if self.details_dialog is not None:
+            self.details_dialog.close()
         QApplication.quit()
 
     # --- Signals
diff --git a/qt/details_dialog.py b/qt/details_dialog.py
index c39f81e2..3c31fa55 100644
--- a/qt/details_dialog.py
+++ b/qt/details_dialog.py
@@ -51,7 +51,7 @@ class DetailsDialog(QDockWidget):
             if not self.titleBarWidget():  # default title bar
                 self.setTitleBarWidget(QWidget())  # disables title bar
                 # Windows (and MacOS?) users cannot move a floating window which
-                # has not native decoration so we force it to dock for now
+                # has no native decoration so we force it to dock for now
                 if not ISLINUX:
                     self.setFloating(False)
         elif self.titleBarWidget() is not None:  # title bar is disabled
diff --git a/qt/pe/details_dialog.py b/qt/pe/details_dialog.py
index 7fe89aa0..d75fc1cb 100644
--- a/qt/pe/details_dialog.py
+++ b/qt/pe/details_dialog.py
@@ -19,7 +19,6 @@ tr = trget("ui")
 class DetailsDialog(DetailsDialogBase):
     def __init__(self, parent, app):
         self.vController = None
-        self.app = app
         super().__init__(parent, app)
 
     def _setupUi(self):