diff --git a/ipv6/co.cidr b/ipv6/co.cidr
index f02d85682..b36912cf3 100644
--- a/ipv6/co.cidr
+++ b/ipv6/co.cidr
@@ -102,6 +102,7 @@
 2801:16:1800::/48
 2801:16:2800::/48
 2801:16:5000::/44
+2801:16:5800::/48
 2801:16:6800::/48
 2801:16:a800::/48
 2801:16:c800::/48