diff --git a/man2/mmap.2 b/man2/mmap.2
index 4e85c1169..e6f96b471 100644
--- a/man2/mmap.2
+++ b/man2/mmap.2
@@ -164,9 +164,7 @@ The mapping is not backed by any file;
 its contents are initialized to zero.
 The
 .I fd
-and
-.I offset
-arguments are ignored;
+argument is ignored;
 however, some implementations require
 .I fd
 to be \-1 if
@@ -175,6 +173,11 @@ to be \-1 if
 .BR MAP_ANON )
 is specified,
 and portable applications should ensure this.
+The
+.I offset
+argument should be zero.
+.\" See the pgoff overflow check in do_mmap().
+.\" See the offset check in sys_mmap in arch/x86/kernel/sys_x86_64.c.
 The use of
 .B MAP_ANONYMOUS
 in conjunction with