diff --git a/src/bluetooth/qleadvertiser_p.h b/src/bluetooth/qleadvertiser_p.h
index bdcfcf1c8109259473eac5cc87652e9097f858a9..ce0c74c76527e2585335545c950e087b84da2e04 100644
--- a/src/bluetooth/qleadvertiser_p.h
+++ b/src/bluetooth/qleadvertiser_p.h
@@ -34,6 +34,17 @@
 #ifndef QLEADVERTISER_P_H
 #define QLEADVERTISER_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 "qlowenergyadvertisingdata.h"
 #include "qlowenergyadvertisingparameters.h"