diff --git a/src/gui/kernel/qwindow.cpp b/src/gui/kernel/qwindow.cpp
index 40e9b9723a..d6f9fad070 100644
--- a/src/gui/kernel/qwindow.cpp
+++ b/src/gui/kernel/qwindow.cpp
@@ -1083,6 +1083,11 @@ Qt::WindowState QWindow::windowState() const
 void QWindow::setTransientParent(QWindow *parent)
 {
     Q_D(QWindow);
+    if (parent && !parent->isTopLevel()) {
+        qWarning() << Q_FUNC_INFO << parent << "must be a top level window.";
+        return;
+    }
+
     d->transientParent = parent;
 
     QGuiApplicationPrivate::updateBlockedStatus(this);
diff --git a/src/widgets/kernel/qwidget_qpa.cpp b/src/widgets/kernel/qwidget_qpa.cpp
index 70d274796b..5a4bd33672 100644
--- a/src/widgets/kernel/qwidget_qpa.cpp
+++ b/src/widgets/kernel/qwidget_qpa.cpp
@@ -138,7 +138,7 @@ void QWidgetPrivate::create_sys(WId window, bool initializeWindow, bool destroyO
     if (QWidget *nativeParent = q->nativeParentWidget()) {
         if (nativeParent->windowHandle()) {
             if (flags & Qt::Window) {
-                win->setTransientParent(nativeParent->windowHandle());
+                win->setTransientParent(nativeParent->window()->windowHandle());
                 win->setParent(0);
             } else {
                 win->setTransientParent(0);
diff --git a/tests/auto/widgets/dialogs/qdialog/tst_qdialog.cpp b/tests/auto/widgets/dialogs/qdialog/tst_qdialog.cpp
index c3d2c4a9e7..cd9ff28891 100644
--- a/tests/auto/widgets/dialogs/qdialog/tst_qdialog.cpp
+++ b/tests/auto/widgets/dialogs/qdialog/tst_qdialog.cpp
@@ -50,6 +50,7 @@
 #include <QVBoxLayout>
 #include <QSizeGrip>
 #include <QDesktopWidget>
+#include <QWindow>
 #include <private/qguiapplication_p.h>
 #include <qpa/qplatformtheme.h>
 #include <qpa/qplatformtheme_p.h>
@@ -85,6 +86,8 @@ private slots:
     void setVisible();
     void reject();
     void snapToDefaultButton();
+    void transientParent_data();
+    void transientParent();
 
 private:
     QDialog *testWidget;
@@ -584,5 +587,34 @@ void tst_QDialog::snapToDefaultButton()
 #endif // !QT_NO_CURSOR
 }
 
+void tst_QDialog::transientParent_data()
+{
+    QTest::addColumn<bool>("nativewidgets");
+    QTest::newRow("Non-native") << false;
+    QTest::newRow("Native") << true;
+}
+
+void tst_QDialog::transientParent()
+{
+    QFETCH(bool, nativewidgets);
+    testWidget->hide();
+    QWidget topLevel;
+    topLevel.resize(200, 200);
+    topLevel.move(QGuiApplication::primaryScreen()->availableGeometry().center() - QPoint(100, 100));
+    QVBoxLayout *layout = new QVBoxLayout(&topLevel);
+    QWidget *innerWidget = new QWidget(&topLevel);
+    layout->addWidget(innerWidget);
+    if (nativewidgets)
+        innerWidget->winId();
+    topLevel.show();
+    QVERIFY(QTest::qWaitForWindowExposed(&topLevel));
+    QDialog dialog(innerWidget);
+    dialog.show();
+    QVERIFY(QTest::qWaitForWindowExposed(&dialog));
+    // Transient parent should always be the top level, also when using
+    // native child widgets.
+    QCOMPARE(dialog.windowHandle()->transientParent(), topLevel.windowHandle());
+}
+
 QTEST_MAIN(tst_QDialog)
 #include "tst_qdialog.moc"