diff --git a/bsd-user/freebsd/meson.build b/bsd-user/freebsd/meson.build
index 8fd6c7cfb8..38f2debf7e 100644
--- a/bsd-user/freebsd/meson.build
+++ b/bsd-user/freebsd/meson.build
@@ -1,6 +1,12 @@
+bsd_syscall_nr = custom_target('bsd-syscall-h',
+    output: '@BASENAME@_nr.h',
+    input: ['/usr/include/sys/syscall.h'],
+    command: [sh, meson.current_source_dir() / 'scripts/syscallhdr.sh', '@INPUT@', '@OUTPUT@', 'FREEBSD'])
+
 bsd_user_ss.add(files(
   'os-stat.c',
   'os-proc.c',
   'os-sys.c',
-  'os-syscall.c',
-))
+  'os-syscall.c'),
+  bsd_syscall_nr
+)
diff --git a/bsd-user/freebsd/scripts/syscallhdr.sh b/bsd-user/freebsd/scripts/syscallhdr.sh
new file mode 100644
index 0000000000..fa38500775
--- /dev/null
+++ b/bsd-user/freebsd/scripts/syscallhdr.sh
@@ -0,0 +1,9 @@
+#!/bin/sh
+# Copyright (c) 2026 Warner Losh <imp@bsdimp.com>
+# SPDX-License-Identifier: GPL-2.0-or-later
+
+in="$1"
+out="$2"
+bsd="$3"
+
+awk -v bsd="$3" '{sub("SYS_", "TARGET_" bsd "_NR_", $0); print;}' < $in > $out