diff --git a/libc/kernel/arch-x86/asm/vsyscall.h b/libc/kernel/arch-x86/asm/vsyscall.h
index a7bee3b..41a52cf 100644
--- a/libc/kernel/arch-x86/asm/vsyscall.h
+++ b/libc/kernel/arch-x86/asm/vsyscall.h
@@ -7,21 +7,28 @@
  ***   structures, and macros generated from the original header, and thus,
  ***   contains no copyrightable information.
  ***
+ ***   To edit the content of this header, modify the corresponding
+ ***   source file (e.g. under external/kernel-headers/original/) then
+ ***   run bionic/libc/kernel/tools/update_all.py
+ ***
+ ***   Any manual change here will be lost the next time this script will
+ ***   be run. You've been warned!
+ ***
  ****************************************************************************
  ****************************************************************************/
 #ifndef _ASM_X86_64_VSYSCALL_H_
 #define _ASM_X86_64_VSYSCALL_H_
-
 enum vsyscall_num {
  __NR_vgettimeofday,
+/* WARNING: DO NOT EDIT, AUTO-GENERATED CODE - SEE TOP FOR INSTRUCTIONS */
  __NR_vtime,
  __NR_vgetcpu,
 };
-
 #define VSYSCALL_START (-10UL << 20)
+/* WARNING: DO NOT EDIT, AUTO-GENERATED CODE - SEE TOP FOR INSTRUCTIONS */
 #define VSYSCALL_SIZE 1024
 #define VSYSCALL_END (-2UL << 20)
 #define VSYSCALL_MAPPED_PAGES 1
 #define VSYSCALL_ADDR(vsyscall_nr) (VSYSCALL_START+VSYSCALL_SIZE*(vsyscall_nr))
-
+/* WARNING: DO NOT EDIT, AUTO-GENERATED CODE - SEE TOP FOR INSTRUCTIONS */
 #endif