diff --git a/src/widgets/widgets/qdockwidget.cpp b/src/widgets/widgets/qdockwidget.cpp
index fe0feeed125..b6576ed131f 100644
--- a/src/widgets/widgets/qdockwidget.cpp
+++ b/src/widgets/widgets/qdockwidget.cpp
@@ -1531,7 +1531,13 @@ void QDockWidget::closeEvent(QCloseEvent *event)
     Q_D(QDockWidget);
     if (d->state)
         d->endDrag(true);
-    QWidget::closeEvent(event);
+
+    // For non-closable widgets, don't allow closing, except when the mainwindow
+    // is hidden, as otherwise an application wouldn't be able to be shut down.
+    const QMainWindow *win = qobject_cast<QMainWindow*>(parentWidget());
+    const bool canClose = (d->features & DockWidgetClosable)
+                       || (!win || !win->isVisible());
+    event->setAccepted(canClose);
 }
 
 /*! \reimp */
diff --git a/tests/auto/widgets/widgets/qdockwidget/tst_qdockwidget.cpp b/tests/auto/widgets/widgets/qdockwidget/tst_qdockwidget.cpp
index 61f8bf995bc..45a8296d5e7 100644
--- a/tests/auto/widgets/widgets/qdockwidget/tst_qdockwidget.cpp
+++ b/tests/auto/widgets/widgets/qdockwidget/tst_qdockwidget.cpp
@@ -73,6 +73,7 @@ private slots:
 
     // test closing and deleting consistency
     void closeAndDelete();
+    void closeUnclosable();
 
     // test save and restore consistency
     void saveAndRestore();
@@ -1585,6 +1586,24 @@ void tst_QDockWidget::closeAndDelete()
 #endif // QT_BUILD_INTERNAL
 }
 
+void tst_QDockWidget::closeUnclosable()
+{
+    QDockWidget *dockWidget = new QDockWidget("dock");
+    dockWidget->setWidget(new QScrollArea);
+    dockWidget->setFeatures(QDockWidget::DockWidgetFloatable);
+
+    QMainWindow mw;
+    mw.addDockWidget(Qt::TopDockWidgetArea, dockWidget);
+    mw.show();
+
+    QVERIFY(QTest::qWaitForWindowExposed(&mw));
+    dockWidget->setFloating(true);
+
+    QCOMPARE(dockWidget->close(), false);
+    mw.close();
+    QCOMPARE(dockWidget->close(), true);
+}
+
 // Test dock area permissions
 void tst_QDockWidget::dockPermissions()
 {