diff --git a/contrib/cvs/man/cvs.1 b/contrib/cvs/man/cvs.1
index a034a6b18d5..968227f0fa0 100644
--- a/contrib/cvs/man/cvs.1
+++ b/contrib/cvs/man/cvs.1
@@ -2123,6 +2123,13 @@ If neither is set, a system-dependent default editor (e.g.,
 .BR vi )
 is used.
 .TP
+.SM CVS_CLIENT_PORT
+If this variable is set then
+.B cvs
+will use this port in
+\fIpserver mode\fP
+rather than the default port (cvspserver 2401).
+.TP
 .SM CVS_IGNORE_REMOTE_ROOT
 If this variable is set then
 .B cvs