diff --git a/libc/kernel/common/linux/highmem.h b/libc/kernel/common/linux/highmem.h
index d4a34ca..88435c8 100644
--- a/libc/kernel/common/linux/highmem.h
+++ b/libc/kernel/common/linux/highmem.h
@@ -7,25 +7,33 @@
  ***   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 _LINUX_HIGHMEM_H
 #define _LINUX_HIGHMEM_H
-
 #include <linux/fs.h>
 #include <linux/mm.h>
-
+/* WARNING: DO NOT EDIT, AUTO-GENERATED CODE - SEE TOP FOR INSTRUCTIONS */
 #include <asm/cacheflush.h>
-
 #ifndef ARCH_HAS_FLUSH_ANON_PAGE
 #endif
 #ifndef ARCH_HAS_FLUSH_KERNEL_DCACHE_PAGE
+/* WARNING: DO NOT EDIT, AUTO-GENERATED CODE - SEE TOP FOR INSTRUCTIONS */
 #endif
 #define kunmap(page) do { (void) (page); } while (0)
 #define kmap_atomic(page, idx) page_address(page)
 #define kunmap_atomic(addr, idx) do { } while (0)
+/* WARNING: DO NOT EDIT, AUTO-GENERATED CODE - SEE TOP FOR INSTRUCTIONS */
 #define kmap_atomic_pfn(pfn, idx) page_address(pfn_to_page(pfn))
 #define kmap_atomic_to_page(ptr) virt_to_page(ptr)
 #ifndef __HAVE_ARCH_ALLOC_ZEROED_USER_HIGHPAGE
 #endif
+/* WARNING: DO NOT EDIT, AUTO-GENERATED CODE - SEE TOP FOR INSTRUCTIONS */
 #endif