diff --git a/src/widgets/widgets/qmainwindowlayout.cpp b/src/widgets/widgets/qmainwindowlayout.cpp
index 2cc7f585d09..a83587a78a0 100644
--- a/src/widgets/widgets/qmainwindowlayout.cpp
+++ b/src/widgets/widgets/qmainwindowlayout.cpp
@@ -276,8 +276,7 @@ public:
 #if QT_CONFIG(toolbar)
     QToolBarAreaLayout *toolBarAreaLayout()
     {
-        auto *mainWindow = static_cast<QMainWindow*>(parentWidget());
-        return qt_mainwindow_layout(mainWindow)->toolBarAreaLayout();
+        return nullptr; // QDockWidgetGroupWindow doesn't have toolbars
     }
 #endif
 
diff --git a/src/widgets/widgets/qmainwindowlayout_p.h b/src/widgets/widgets/qmainwindowlayout_p.h
index e2770fd58d5..7e22788ec49 100644
--- a/src/widgets/widgets/qmainwindowlayout_p.h
+++ b/src/widgets/widgets/qmainwindowlayout_p.h
@@ -289,7 +289,7 @@ QList<int> QMainWindowLayoutSeparatorHelper<Layout>::findSeparator(const QPoint
     Layout *layout = const_cast<Layout*>(this->layout());
 #if QT_CONFIG(toolbar)
     QToolBarAreaLayout *toolBarAreaLayout = layout->toolBarAreaLayout();
-    if (!toolBarAreaLayout->isEmpty()) {
+    if (toolBarAreaLayout && !toolBarAreaLayout->isEmpty()) {
         // We might have a toolbar that is currently expanded, covering
         // parts of the dock area, in which case we don't want the dock
         // area layout to treat mouse events for the expanded toolbar as