diff --git a/src/gui/kernel/qguiapplication_p.h b/src/gui/kernel/qguiapplication_p.h
index c9eb6722208..173f4e6ba2c 100644
--- a/src/gui/kernel/qguiapplication_p.h
+++ b/src/gui/kernel/qguiapplication_p.h
@@ -42,6 +42,17 @@
 #ifndef QGUIAPPLICATION_P_H
 #define QGUIAPPLICATION_P_H
 
+//
+//  W A R N I N G
+//  -------------
+//
+// This file is not part of the Qt API.  It exists purely as an
+// implementation detail.  This header file may change from version to
+// version without notice, or even be removed.
+//
+// We mean it.
+//
+
 #include <QtGui/qguiapplication.h>
 
 #include <QtCore/QPointF>
diff --git a/src/gui/kernel/qinputmethod_p.h b/src/gui/kernel/qinputmethod_p.h
index f35d135e5d9..566b341b512 100644
--- a/src/gui/kernel/qinputmethod_p.h
+++ b/src/gui/kernel/qinputmethod_p.h
@@ -42,6 +42,17 @@
 #ifndef QINPUTMETHOD_P_H
 #define QINPUTMETHOD_P_H
 
+//
+//  W A R N I N G
+//  -------------
+//
+// This file is not part of the Qt API.  It exists purely as an
+// implementation detail.  This header file may change from version to
+// version without notice, or even be removed.
+//
+// We mean it.
+//
+
 #include <qinputmethod.h>
 #include <private/qobject_p.h>
 #include <QtCore/QWeakPointer>
diff --git a/src/gui/kernel/qopenglcontext_p.h b/src/gui/kernel/qopenglcontext_p.h
index efce991679d..198528dc4a0 100644
--- a/src/gui/kernel/qopenglcontext_p.h
+++ b/src/gui/kernel/qopenglcontext_p.h
@@ -42,6 +42,17 @@
 #ifndef QOPENGLCONTEXT_P_H
 #define QOPENGLCONTEXT_P_H
 
+//
+//  W A R N I N G
+//  -------------
+//
+// This file is not part of the Qt API.  It exists purely as an
+// implementation detail.  This header file may change from version to
+// version without notice, or even be removed.
+//
+// We mean it.
+//
+
 #ifndef QT_NO_OPENGL
 
 #include "qopengl.h"
diff --git a/src/gui/kernel/qplatforminputcontext_p.h b/src/gui/kernel/qplatforminputcontext_p.h
index 3dc2ad2a0f5..19a3619667f 100644
--- a/src/gui/kernel/qplatforminputcontext_p.h
+++ b/src/gui/kernel/qplatforminputcontext_p.h
@@ -42,6 +42,17 @@
 #ifndef QPLATFORMINPUTCONTEXT_P_H
 #define QPLATFORMINPUTCONTEXT_P_H
 
+//
+//  W A R N I N G
+//  -------------
+//
+// This file is not part of the Qt API.  It exists purely as an
+// implementation detail.  This header file may change from version to
+// version without notice, or even be removed.
+//
+// We mean it.
+//
+
 #include <private/qobject_p.h>
 
 QT_BEGIN_HEADER
diff --git a/src/gui/kernel/qscreen_p.h b/src/gui/kernel/qscreen_p.h
index f3b6082c157..aea108f926e 100644
--- a/src/gui/kernel/qscreen_p.h
+++ b/src/gui/kernel/qscreen_p.h
@@ -42,6 +42,17 @@
 #ifndef QSCREEN_P_H
 #define QSCREEN_P_H
 
+//
+//  W A R N I N G
+//  -------------
+//
+// This file is not part of the Qt API.  It exists purely as an
+// implementation detail.  This header file may change from version to
+// version without notice, or even be removed.
+//
+// We mean it.
+//
+
 #include <QtGui/qscreen.h>
 #include <qpa/qplatformscreen.h>
 
diff --git a/src/gui/kernel/qtouchdevice_p.h b/src/gui/kernel/qtouchdevice_p.h
index e58c795653b..ff6e0ffb01c 100644
--- a/src/gui/kernel/qtouchdevice_p.h
+++ b/src/gui/kernel/qtouchdevice_p.h
@@ -42,6 +42,17 @@
 #ifndef QTOUCHDEVICE_P_H
 #define QTOUCHDEVICE_P_H
 
+//
+//  W A R N I N G
+//  -------------
+//
+// This file is not part of the Qt API.  It exists purely as an
+// implementation detail.  This header file may change from version to
+// version without notice, or even be removed.
+//
+// We mean it.
+//
+
 #include <QtCore/qobject.h>
 #include <QtGui/qtouchdevice.h>
 
diff --git a/src/gui/kernel/qwindow_p.h b/src/gui/kernel/qwindow_p.h
index e522368e84b..fcc55401854 100644
--- a/src/gui/kernel/qwindow_p.h
+++ b/src/gui/kernel/qwindow_p.h
@@ -42,6 +42,17 @@
 #ifndef QWINDOW_P_H
 #define QWINDOW_P_H
 
+//
+//  W A R N I N G
+//  -------------
+//
+// This file is not part of the Qt API.  It exists purely as an
+// implementation detail.  This header file may change from version to
+// version without notice, or even be removed.
+//
+// We mean it.
+//
+
 #include <QtGui/qwindow.h>
 #include <qpa/qplatformwindow.h>
 
@@ -52,7 +63,6 @@ QT_BEGIN_HEADER
 
 QT_BEGIN_NAMESPACE
 
-
 #define QWINDOWSIZE_MAX ((1<<24)-1)
 
 class Q_GUI_EXPORT QWindowPrivate : public QObjectPrivate
diff --git a/src/gui/kernel/qwindowsysteminterface_p.h b/src/gui/kernel/qwindowsysteminterface_p.h
index 1b5351db719..5867337de69 100644
--- a/src/gui/kernel/qwindowsysteminterface_p.h
+++ b/src/gui/kernel/qwindowsysteminterface_p.h
@@ -41,6 +41,17 @@
 #ifndef QWINDOWSYSTEMINTERFACE_P_H
 #define QWINDOWSYSTEMINTERFACE_P_H
 
+//
+//  W A R N I N G
+//  -------------
+//
+// This file is not part of the Qt API.  It exists purely as an
+// implementation detail.  This header file may change from version to
+// version without notice, or even be removed.
+//
+// We mean it.
+//
+
 #include "qwindowsysteminterface.h"
 
 #include <QElapsedTimer>