diff --git a/libc/kernel/common/asm-generic/4level-fixup.h b/libc/kernel/common/asm-generic/4level-fixup.h
index 91ae7f4..dddba1b 100644
--- a/libc/kernel/common/asm-generic/4level-fixup.h
+++ b/libc/kernel/common/asm-generic/4level-fixup.h
@@ -7,36 +7,40 @@
  ***   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 _4LEVEL_FIXUP_H
 #define _4LEVEL_FIXUP_H
-
 #define __ARCH_HAS_4LEVEL_HACK
 #define __PAGETABLE_PUD_FOLDED
-
+/* WARNING: DO NOT EDIT, AUTO-GENERATED CODE - SEE TOP FOR INSTRUCTIONS */
 #define PUD_SIZE PGDIR_SIZE
 #define PUD_MASK PGDIR_MASK
 #define PTRS_PER_PUD 1
-
 #define pud_t pgd_t
-
+/* WARNING: DO NOT EDIT, AUTO-GENERATED CODE - SEE TOP FOR INSTRUCTIONS */
 #define pmd_alloc(mm, pud, address)   ((unlikely(pgd_none(*(pud))) && __pmd_alloc(mm, pud, address))?   NULL: pmd_offset(pud, address))
-
 #define pud_alloc(mm, pgd, address) (pgd)
 #define pud_offset(pgd, start) (pgd)
 #define pud_none(pud) 0
+/* WARNING: DO NOT EDIT, AUTO-GENERATED CODE - SEE TOP FOR INSTRUCTIONS */
 #define pud_bad(pud) 0
 #define pud_present(pud) 1
 #define pud_ERROR(pud) do { } while (0)
 #define pud_clear(pud) pgd_clear(pud)
-
+/* WARNING: DO NOT EDIT, AUTO-GENERATED CODE - SEE TOP FOR INSTRUCTIONS */
 #undef pud_free_tlb
 #define pud_free_tlb(tlb, x) do { } while (0)
 #define pud_free(x) do { } while (0)
 #define __pud_free_tlb(tlb, x) do { } while (0)
-
+/* WARNING: DO NOT EDIT, AUTO-GENERATED CODE - SEE TOP FOR INSTRUCTIONS */
 #undef pud_addr_end
 #define pud_addr_end(addr, end) (end)
-
 #endif