diff --git a/examples/widgets/mainwindows/mainwindow/toolbar.cpp b/examples/widgets/mainwindows/mainwindow/toolbar.cpp
index 66f26d7a72..d73c12f50d 100644
--- a/examples/widgets/mainwindows/mainwindow/toolbar.cpp
+++ b/examples/widgets/mainwindows/mainwindow/toolbar.cpp
@@ -37,8 +37,9 @@ static QPixmap genIcon(const QSize &iconSize, const QString &, const QColor &col
 static QPixmap genIcon(const QSize &iconSize, int number, const QColor &color, qreal pixelRatio)
 { return genIcon(iconSize, QString::number(number), color, pixelRatio); }
 
-ToolBar::ToolBar(const QString &title, QWidget *parent)
-    : QToolBar(parent)
+ToolBar::ToolBar(const QString &title, QMainWindow *mainWindow)
+    : QToolBar(mainWindow)
+    , mainWindow(mainWindow)
     , spinbox(nullptr)
     , spinboxAction(nullptr)
 {
@@ -161,9 +162,6 @@ ToolBar::ToolBar(const QString &title, QWidget *parent)
 
 void ToolBar::updateMenu()
 {
-    QMainWindow *mainWindow = qobject_cast<QMainWindow *>(parentWidget());
-    Q_ASSERT(mainWindow);
-
     const Qt::ToolBarArea area = mainWindow->toolBarArea(this);
     const Qt::ToolBarAreas areas = allowedAreas();
 
@@ -267,9 +265,6 @@ void ToolBar::place(Qt::ToolBarArea area, bool p)
     if (!p)
         return;
 
-    QMainWindow *mainWindow = qobject_cast<QMainWindow *>(parentWidget());
-    Q_ASSERT(mainWindow);
-
     mainWindow->addToolBar(area, this);
 
     if (allowedAreasActions->isEnabled()) {
@@ -309,8 +304,5 @@ void ToolBar::placeBottom(bool p)
 
 void ToolBar::insertToolBarBreak()
 {
-    QMainWindow *mainWindow = qobject_cast<QMainWindow *>(parentWidget());
-    Q_ASSERT(mainWindow);
-
     mainWindow->insertToolBarBreak(this);
 }
diff --git a/examples/widgets/mainwindows/mainwindow/toolbar.h b/examples/widgets/mainwindows/mainwindow/toolbar.h
index 14eca61684..0030adbe23 100644
--- a/examples/widgets/mainwindows/mainwindow/toolbar.h
+++ b/examples/widgets/mainwindows/mainwindow/toolbar.h
@@ -16,7 +16,7 @@ class ToolBar : public QToolBar
     Q_OBJECT
 
 public:
-    explicit ToolBar(const QString &title, QWidget *parent);
+    explicit ToolBar(const QString &title, QMainWindow *mainWindow);
 
     QMenu *toolbarMenu() const { return menu; }
 
@@ -45,6 +45,8 @@ private:
     void allow(Qt::ToolBarArea area, bool allow);
     void place(Qt::ToolBarArea area, bool place);
 
+    QMainWindow *mainWindow;
+
     QSpinBox *spinbox;
     QAction *spinboxAction;