diff --git a/telnet/telnet.1 b/telnet/telnet.1
index 06b2b8e..9841462 100644
--- a/telnet/telnet.1
+++ b/telnet/telnet.1
@@ -1009,6 +1009,10 @@ Displays the legal
 .Pq Ic unset
 commands.
 .El
+.It Ic skey Ar sequence challenge
+The
+.Ic skey
+command computes a response to the S/Key challenge.
 .It Ic slc Ar state 
 The
 .Ic slc