diff --git a/src/DockWidgetBase.cpp b/src/DockWidgetBase.cpp
index c9ce8c89..9a4f1b5b 100644
--- a/src/DockWidgetBase.cpp
+++ b/src/DockWidgetBase.cpp
@@ -205,11 +205,13 @@ void DockWidgetBase::addDockWidgetAsTab(DockWidgetBase *other, InitialOption opt
     frame->addWidget(other, option);
 }
 
-void DockWidgetBase::addDockWidgetToContainingWindow(DockWidgetBase *other, Location location, DockWidgetBase *relativeTo)
+void DockWidgetBase::addDockWidgetToContainingWindow(DockWidgetBase *other,
+                                                     Location location,
+                                                     DockWidgetBase *relativeTo)
 {
-    qCDebug(addwidget) << Q_FUNC_INFO << other << location << relativeTo;
-    if (qobject_cast<MainWindowBase*>(window())) {
-        qWarning() << Q_FUNC_INFO << "Just use MainWindow::addWidget() directly. This function is for floating nested windows only.";
+    if (auto mainWindow = qobject_cast<MainWindowBase*>(window())) {
+        // It's inside a main window. Simply use the main window API.
+        mainWindow->addDockWidget(other, location, relativeTo);
         return;
     }
 
diff --git a/tests/tst_docks.cpp b/tests/tst_docks.cpp
index cf789f2b..af91b7c3 100644
--- a/tests/tst_docks.cpp
+++ b/tests/tst_docks.cpp
@@ -3922,27 +3922,37 @@ void TestDocks::tst_addDockWidgetToMainWindow()
 
 void TestDocks::tst_addDockWidgetToContainingWindow()
 {
-    EnsureTopLevelsDeleted e;
+    { // Test with a floating window
+        EnsureTopLevelsDeleted e;
 
-    auto dock1 = createDockWidget("dock1", new QPushButton("one"));
-    auto dock2 = createDockWidget("dock2", new QPushButton("two"));
-    auto dock3 = createDockWidget("dock3", new QPushButton("three"));
+        auto dock1 = createDockWidget("dock1", new QPushButton("one"));
+        auto dock2 = createDockWidget("dock2", new QPushButton("two"));
+        auto dock3 = createDockWidget("dock3", new QPushButton("three"));
 
-    dock1->addDockWidgetToContainingWindow(dock2, Location_OnRight);
-    dock1->addDockWidgetToContainingWindow(dock3, Location_OnTop, dock2);
+        dock1->addDockWidgetToContainingWindow(dock2, Location_OnRight);
+        dock1->addDockWidgetToContainingWindow(dock3, Location_OnTop, dock2);
 
-    QCOMPARE(dock1->window(), dock2->window());
-    QCOMPARE(dock2->window(), dock3->window());
+        QCOMPARE(dock1->window(), dock2->window());
+        QCOMPARE(dock2->window(), dock3->window());
 
-    QVERIFY(dock3->frame()->QWidgetAdapter::y() < dock2->frame()->QWidgetAdapter::y());
-    QVERIFY(dock1->frame()->QWidgetAdapter::x() < dock2->frame()->QWidgetAdapter::x());
-    QCOMPARE(dock2->frame()->QWidgetAdapter::x(), dock3->frame()->QWidgetAdapter::x());
+        QVERIFY(dock3->frame()->QWidgetAdapter::y() < dock2->frame()->QWidgetAdapter::y());
+        QVERIFY(dock1->frame()->QWidgetAdapter::x() < dock2->frame()->QWidgetAdapter::x());
+        QCOMPARE(dock2->frame()->QWidgetAdapter::x(), dock3->frame()->QWidgetAdapter::x());
+    }
 
-    auto window = dock1->window();
-    delete dock1;
-    delete dock2;
-    delete dock3;
-    Testing::waitForDeleted(window);
+    { // Also test with a main window
+        EnsureTopLevelsDeleted e;
+
+        auto m = createMainWindow();
+        auto dock1 = createDockWidget("dock1", new QPushButton("one"));
+        auto dock2 = createDockWidget("dock2", new QPushButton("two"));
+
+        m->addDockWidget(dock1, Location_OnRight, nullptr);
+        dock1->addDockWidgetToContainingWindow(dock2, Location_OnRight);
+
+        QCOMPARE(dock1->window(), dock2->window());
+        QCOMPARE(m.get(), dock2->window());
+    }
 }
 
 void TestDocks::tst_notClosable()