1 files changed, 5 insertions, 0 deletions
diff --git a/src/gui/kernel/qwindow.cpp b/src/gui/kernel/qwindow.cpp
index 327544c59c..8159b7746e 100644
--- a/src/gui/kernel/qwindow.cpp
+++ b/src/gui/kernel/qwindow.cpp
@@ -1119,6 +1119,11 @@ 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);