diff --git a/src/corelib/global/qoperatingsystemversion_p.h b/src/corelib/global/qoperatingsystemversion_p.h
index f227e98dd1..78d0daf0c6 100644
--- a/src/corelib/global/qoperatingsystemversion_p.h
+++ b/src/corelib/global/qoperatingsystemversion_p.h
@@ -37,6 +37,20 @@
 **
 ****************************************************************************/
 
+#ifndef QOPERATINGSYSTEMVERSION_P_H
+#define QOPERATINGSYSTEMVERSION_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 "qoperatingsystemversion.h"
 
 #ifdef Q_OS_WIN
@@ -69,3 +83,5 @@ static inline QOperatingSystemVersion::OSType currentType()
 }
 
 QT_END_NAMESPACE
+
+#endif // QOPERATINGSYSTEMVERSION_P_H