diff --git a/usr.bin/top/top.1 b/usr.bin/top/top.1
index b3b2cddb3ca1..03301b2f89fc 100644
--- a/usr.bin/top/top.1
+++ b/usr.bin/top/top.1
@@ -103,7 +103,7 @@ Toggle displaying thread ID (tid) instead of process id (pid).
 Do not display the
 .Nm
 process itself.
-.It Fl m
+.It Fl m Ar display
 Display either 'cpu' or 'io' statistics.
 Default is 'cpu'.
 .It Fl n