diff --git a/inventory/host_vars/smtp-mm-osuosl01.fedoraproject.org b/inventory/host_vars/smtp-mm-osuosl01.fedoraproject.org
index f5482cdb71..a761d48353 100644
--- a/inventory/host_vars/smtp-mm-osuosl01.fedoraproject.org
+++ b/inventory/host_vars/smtp-mm-osuosl01.fedoraproject.org
@@ -8,6 +8,7 @@ eth0_ipv4_ip: 140.211.169.205
 eth0_ipv4_nm: 25
 eth0_ipv6_ip: "2605:bc80:3010:600:dead:beef:cafe:fedb"
 eth0_ipv6_gw: "2605:bc80:3010:600::1"
+eth0_ipv6_nm: 64
 has_ipv6: yes
 ks_repo: http://infrastructure.fedoraproject.org/repo/rhel/RHEL9-x86_64/
 ks_url: http://infrastructure.fedoraproject.org/repo/rhel/ks/kvm-rhel