--- OS/os.c-FreeBSD.orig	2021-10-11 17:03:56.119681000 +0200
+++ OS/os.c-FreeBSD	2021-10-11 17:04:27.802597000 +0200
@@ -16,10 +16,11 @@
 ssize_t
 os_sendfile(int out, int in, off_t * offp, size_t cnt)
 {
-off_t loff = *offp, written;
+off_t loff = offp ? *offp : 0;
+off_t written;

 if (sendfile(in, out, loff, cnt, NULL, &written, 0) < 0) return (ssize_t)-1;
-*offp = loff + written;
+if (offp) *offp = loff + written;
 return (ssize_t)written;
 }