diff --git a/src/gui/kernel/qplatformwindow_qpa.cpp b/src/gui/kernel/qplatformwindow_qpa.cpp
index b36a2771f3..e07ed78615 100644
--- a/src/gui/kernel/qplatformwindow_qpa.cpp
+++ b/src/gui/kernel/qplatformwindow_qpa.cpp
@@ -310,6 +310,17 @@ bool QPlatformWindow::setMouseGrabEnabled(bool grab)
     return false;
 }
 
+/*!
+    Reimplement to be able to let Qt indicate that the window has been
+    modified. Return true if the native window supports setting the modified
+    flag, false otherwise.
+*/
+bool QPlatformWindow::setWindowModified(bool modified)
+{
+    Q_UNUSED(modified);
+    return false;
+}
+
 /*!
     Reimplement this method to be able to do any platform specific event
     handling. All events for window() are passed to this function before being
diff --git a/src/gui/kernel/qplatformwindow_qpa.h b/src/gui/kernel/qplatformwindow_qpa.h
index 31b14ca97d..aa4d7f5054 100644
--- a/src/gui/kernel/qplatformwindow_qpa.h
+++ b/src/gui/kernel/qplatformwindow_qpa.h
@@ -113,6 +113,8 @@ public:
     virtual bool setKeyboardGrabEnabled(bool grab);
     virtual bool setMouseGrabEnabled(bool grab);
 
+    virtual bool setWindowModified(bool modified);
+
     virtual void windowEvent(QEvent *event);
 
 protected:
diff --git a/src/plugins/platforms/cocoa/qcocoawindow.h b/src/plugins/platforms/cocoa/qcocoawindow.h
index 184422a04a..68cf72b0fb 100644
--- a/src/plugins/platforms/cocoa/qcocoawindow.h
+++ b/src/plugins/platforms/cocoa/qcocoawindow.h
@@ -117,6 +117,8 @@ public:
     void setCurrentContext(QCocoaGLContext *context);
     QCocoaGLContext *currentContext() const;
 
+    Q_DECL_OVERRIDE bool setWindowModified(bool modified);
+
 protected:
     // NSWindow handling. The QCocoaWindow/QNSView can either be displayed
     // in an existing NSWindow or in one created by Qt.
diff --git a/src/plugins/platforms/cocoa/qcocoawindow.mm b/src/plugins/platforms/cocoa/qcocoawindow.mm
index af8f039d94..f3458c2540 100644
--- a/src/plugins/platforms/cocoa/qcocoawindow.mm
+++ b/src/plugins/platforms/cocoa/qcocoawindow.mm
@@ -503,3 +503,10 @@ QCocoaWindow *QCocoaWindow::parentCocoaWindow() const
     return 0;
 }
 
+bool QCocoaWindow::setWindowModified(bool modified)
+{
+    if (!m_nsWindow)
+        return false;
+    [m_nsWindow setDocumentEdited:(modified?YES:NO)];
+    return true;
+}
diff --git a/src/widgets/kernel/qwidget.cpp b/src/widgets/kernel/qwidget.cpp
index 662c9b7403..ddab66944e 100644
--- a/src/widgets/kernel/qwidget.cpp
+++ b/src/widgets/kernel/qwidget.cpp
@@ -10322,20 +10322,30 @@ void QWidget::setWindowModified(bool mod)
     Q_D(QWidget);
     setAttribute(Qt::WA_WindowModified, mod);
 
-#ifndef Q_WS_MAC
-    if (!windowTitle().contains(QLatin1String("[*]")) && mod)
-        qWarning("QWidget::setWindowModified: The window title does not contain a '[*]' placeholder");
-#endif
-    d->setWindowTitle_helper(windowTitle());
-    d->setWindowIconText_helper(windowIconText());
-#ifdef Q_WS_MAC
-    d->setWindowModified_sys(mod);
-#endif
+    d->setWindowModified_helper();
 
     QEvent e(QEvent::ModifiedChange);
     QApplication::sendEvent(this, &e);
 }
 
+void QWidgetPrivate::setWindowModified_helper()
+{
+    Q_Q(QWidget);
+    QWindow *window = q->windowHandle();
+    if (!window)
+        return;
+    QPlatformWindow *platformWindow = window->handle();
+    if (!platformWindow)
+        return;
+    bool on = q->testAttribute(Qt::WA_WindowModified);
+    if (!platformWindow->setWindowModified(on)) {
+        if (!q->windowTitle().contains(QLatin1String("[*]")) && on)
+            qWarning("QWidget::setWindowModified: The window title does not contain a '[*]' placeholder");
+        setWindowTitle_helper(q->windowTitle());
+        setWindowIconText_helper(q->windowIconText());
+    }
+}
+
 #ifndef QT_NO_TOOLTIP
 /*!
   \property QWidget::toolTip
diff --git a/src/widgets/kernel/qwidget_p.h b/src/widgets/kernel/qwidget_p.h
index d3fcdce6a8..d7c0ec75b0 100644
--- a/src/widgets/kernel/qwidget_p.h
+++ b/src/widgets/kernel/qwidget_p.h
@@ -466,6 +466,7 @@ public:
 
     void setWindowTitle_helper(const QString &cap);
     void setWindowFilePath_helper(const QString &filePath);
+    void setWindowModified_helper();
 
     bool setMinimumSize_helper(int &minw, int &minh);
     bool setMaximumSize_helper(int &maxw, int &maxh);
@@ -745,7 +746,6 @@ public:
     void update_sys(const QRect &rect);
     void update_sys(const QRegion &rgn);
     void setGeometry_sys_helper(int, int, int, int, bool);
-    void setWindowModified_sys(bool b);
     void updateMaximizeButton_sys();
     void setWindowFilePath_sys(const QString &filePath);
     void createWindow_sys();
diff --git a/src/widgets/kernel/qwidget_qpa.cpp b/src/widgets/kernel/qwidget_qpa.cpp
index 4fe7ad6dc7..6b6dd12703 100644
--- a/src/widgets/kernel/qwidget_qpa.cpp
+++ b/src/widgets/kernel/qwidget_qpa.cpp
@@ -140,6 +140,7 @@ void QWidgetPrivate::create_sys(WId window, bool initializeWindow, bool destroyO
             q->setAttribute(Qt::WA_PaintOnScreen, true);
     }
 
+    setWindowModified_helper();
     setWinId(win->winId());
 
 //    first check children. and create them if necessary