diff --git a/man/man8/ip-netns.8 b/man/man8/ip-netns.8
index 39a10e76..961bcf03 100644
--- a/man/man8/ip-netns.8
+++ b/man/man8/ip-netns.8
@@ -31,6 +31,9 @@ ip-netns \- process network namespace management
 .B ip netns set
 .I NETNSNAME NETNSID
 
+.ti -8
+.IR NETNSID " := " auto " | " POSITIVE-INT
+
 .ti -8
 .BR "ip netns identify"
 .RI "[ " PID " ]"