diff --git a/src/widgets/widgets/qmdisubwindow.cpp b/src/widgets/widgets/qmdisubwindow.cpp
index 89d77574f0..1c03b02ab8 100644
--- a/src/widgets/widgets/qmdisubwindow.cpp
+++ b/src/widgets/widgets/qmdisubwindow.cpp
@@ -263,11 +263,28 @@ static inline ControlElement<T> *ptr(QWidget *widget)
     return nullptr;
 }
 
+QString QMdiSubWindowPrivate::originalWindowTitleHelper() const
+{
+    Q_Q(const QMdiSubWindow);
+    // QTBUG-92240: When DontMaximizeSubWindowOnActivation is set and
+    // there is another subwindow maximized, use its original title.
+    if (auto *mdiArea = q->mdiArea()) {
+        const auto &subWindows = mdiArea->subWindowList();
+        for (auto *subWindow : subWindows) {
+            if (subWindow != q && subWindow->isMaximized()) {
+                auto *subWindowD = static_cast<QMdiSubWindowPrivate *>(qt_widget_private(subWindow));
+                if (!subWindowD->originalTitle.isNull())
+                    return subWindowD->originalTitle;
+            }
+        }
+    }
+    return q->window()->windowTitle();
+}
+
 QString QMdiSubWindowPrivate::originalWindowTitle()
 {
-    Q_Q(QMdiSubWindow);
     if (originalTitle.isNull()) {
-        originalTitle = q->window()->windowTitle();
+        originalTitle = originalWindowTitleHelper();
         if (originalTitle.isNull())
             originalTitle = QLatin1String("");
     }
@@ -282,11 +299,17 @@ void QMdiSubWindowPrivate::setNewWindowTitle()
         return;
     QString original = originalWindowTitle();
     if (!original.isEmpty()) {
-        if (!original.contains(QMdiSubWindow::tr("- [%1]").arg(childTitle)))
-            q->window()->setWindowTitle(QMdiSubWindow::tr("%1 - [%2]").arg(original, childTitle));
+        if (!original.contains(QMdiSubWindow::tr("- [%1]").arg(childTitle))) {
+            auto title = QMdiSubWindow::tr("%1 - [%2]").arg(original, childTitle);
+            ignoreWindowTitleChange = true;
+            q->window()->setWindowTitle(title);
+            ignoreWindowTitleChange = false;
+        }
 
     } else {
+        ignoreWindowTitleChange = true;
         q->window()->setWindowTitle(childTitle);
+        ignoreWindowTitleChange = false;
     }
 }
 
diff --git a/src/widgets/widgets/qmdisubwindow_p.h b/src/widgets/widgets/qmdisubwindow_p.h
index d3513b6708..043cf92201 100644
--- a/src/widgets/widgets/qmdisubwindow_p.h
+++ b/src/widgets/widgets/qmdisubwindow_p.h
@@ -286,6 +286,7 @@ public:
 #endif
     void updateInternalWindowTitle();
     QString originalWindowTitle();
+    QString originalWindowTitleHelper() const;
     void setNewWindowTitle();
 
     inline int titleBarHeight() const
diff --git a/tests/auto/widgets/widgets/qmdiarea/tst_qmdiarea.cpp b/tests/auto/widgets/widgets/qmdiarea/tst_qmdiarea.cpp
index 6df7c74bdc..225b349f08 100644
--- a/tests/auto/widgets/widgets/qmdiarea/tst_qmdiarea.cpp
+++ b/tests/auto/widgets/widgets/qmdiarea/tst_qmdiarea.cpp
@@ -1,4 +1,4 @@
-/****************************************************************************
+/****************************************************************************
 **
 ** Copyright (C) 2016 The Qt Company Ltd.
 ** Contact: https://www.qt.io/licensing/
@@ -281,6 +281,8 @@ private slots:
     void nativeSubWindows();
     void task_209615();
     void task_236750();
+    void qtbug92240_title_data();
+    void qtbug92240_title();
 
 private:
     QMdiSubWindow *activeWindow;
@@ -2697,6 +2699,45 @@ void tst_QMdiArea::task_236750()
     subWindow->showMinimized();
 }
 
+// QTBUG-92240: When subwindows are maximized, their title is supposed to
+// appear on the main window. When DontMaximizeSubWindowOnActivation was set,
+// titles of previously created maximized windows interfered, resulting in
+// "QTBUG-92240 - [1] - [2]".
+void tst_QMdiArea::qtbug92240_title_data()
+{
+    QTest::addColumn<bool>("dontMaximize");
+    QTest::newRow("default") << false;
+    QTest::newRow("dontMaximize") << true;
+}
+
+void tst_QMdiArea::qtbug92240_title()
+{
+    QFETCH(bool, dontMaximize);
+
+#ifdef Q_OS_MACOS
+    QSKIP("Not supported on macOS");
+#endif
+
+    QMainWindow w;
+    const QString title = QStringLiteral("QTBUG-92240");
+    w.setWindowTitle(title);
+    w.menuBar()->addMenu(QStringLiteral("File"));
+    w.show();
+
+    auto *mdiArea = new QMdiArea;
+    w.setCentralWidget(mdiArea);
+    if (dontMaximize)
+        mdiArea->setOption(QMdiArea::DontMaximizeSubWindowOnActivation);
+    auto *sw1 = mdiArea->addSubWindow(new QWidget);
+    sw1->setWindowTitle(QStringLiteral("1"));
+    sw1->showMaximized();
+    QTRY_COMPARE(w.windowTitle(), QLatin1String("QTBUG-92240 - [1]"));
+    auto *sw2 = mdiArea->addSubWindow(new QWidget);
+    sw2->setWindowTitle(QStringLiteral("2"));
+    sw2->showMaximized();
+    QTRY_COMPARE(w.windowTitle(), QLatin1String("QTBUG-92240 - [2]"));
+}
+
 QTEST_MAIN(tst_QMdiArea)
 #include "tst_qmdiarea.moc"