diff --git a/libc/kernel/common/linux/calc64.h b/libc/kernel/common/linux/calc64.h
index 9f726aa..8137ab5 100644
--- a/libc/kernel/common/linux/calc64.h
+++ b/libc/kernel/common/linux/calc64.h
@@ -7,16 +7,22 @@
  ***   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_CALC64_H
 #define _LINUX_CALC64_H
-
 #include <linux/types.h>
 #include <asm/div64.h>
-
+/* WARNING: DO NOT EDIT, AUTO-GENERATED CODE - SEE TOP FOR INSTRUCTIONS */
 #ifndef div_long_long_rem
 #define div_long_long_rem(dividend, divisor, remainder)   do_div_llr((dividend), divisor, remainder)
-
 #endif
 #endif
+/* WARNING: DO NOT EDIT, AUTO-GENERATED CODE - SEE TOP FOR INSTRUCTIONS */