diff --git a/manual/tunables.texi b/manual/tunables.texi
index 1ac58b9ae9..ca92bc980d 100644
--- a/manual/tunables.texi
+++ b/manual/tunables.texi
@@ -669,6 +669,12 @@ This tunable is specific to x86-64 and effective only when the lazy
 binding is disabled.
 @end deftp
 
+@deftp Tunable glibc.cpu.aarch64_gcs
+This tunable name is reserved for future use.
+
+This tunable is specific to AArch64.
+@end deftp
+
 @node Memory Related Tunables
 @section Memory Related Tunables
 @cindex memory related tunables