diff --git a/man2/syscalls.2 b/man2/syscalls.2
index d1c4eb423..706c60daf 100644
--- a/man2/syscalls.2
+++ b/man2/syscalls.2
@@ -838,6 +838,8 @@ that corresponds directly to
 .IR sys_select ()
 and similarly
 .IR __NR_mmap2 .
+s390x is the only 64-bit architecture that has
+.IR old_mmap ().
 .\" .PP
 .\" Two system call numbers,
 .\" .IR __NR__llseek