diff --git a/c-programming/mem/safe_mem.h b/c-programming/mem/safe_mem.h
index 67503af..d426a7f 100644
--- a/c-programming/mem/safe_mem.h
+++ b/c-programming/mem/safe_mem.h
@@ -6,6 +6,9 @@
  * NOTE: Declare macro SAFE_MEM_OLD_BSD when compiling if you're using OpenBSD
  * version earlier than 5.5 or FreeBSD version earlier than 11.0.
  *
+ * NOTE: See https://git.savannah.gnu.org/gitweb/?p=gnulib.git;a=blob_plain;
+ * f=lib/memset_explicit.c;hb=refs/heads/stable-202301
+ *
  * Author: Intel A80486DX2-66
  * License: Creative Commons Zero 1.0 Universal
  */