diff --git a/module/mescc/x86_64/as.scm b/module/mescc/x86_64/as.scm
index 8dbe3476..56dc2df6 100644
--- a/module/mescc/x86_64/as.scm
+++ b/module/mescc/x86_64/as.scm
@@ -1,5 +1,5 @@
 ;;; GNU Mes --- Maxwell Equations of Software
-;;; Copyright © 2018 Jan (janneke) Nieuwenhuizen <janneke@gnu.org>
+;;; Copyright © 2018, 2022 Jan (janneke) Nieuwenhuizen <janneke@gnu.org>
 ;;; Copyright © 2023 Andrius Štikonas <andrius@stikonas.eu>
 ;;; Copyright © 2021 W. J. van der Laan <laanwj@protonmail.com>
 ;;;
@@ -69,9 +69,8 @@
 
 (define (x86_64:function-locals . rest)
   `(
-    ;; FIXME: how on x86_64?
-    ("sub____$i32,%rsp" (#:immediate ,(+ (* 4 1025) (* 20 8))))
-    )) ; 4*1024 buf, 20 local vars
+    ("sub____$i32,%rsp" (#:immediate ,(+ (* 8 1025) (* 20 8))))
+    )) ; 8*1024 buf, 20 local vars
 
 (define (x86_64:r->local info n)
   (let ((r (get-r info))