diff --git a/docs/getting-started-guides/coreos/units/apiserver.service b/docs/getting-started-guides/coreos/units/apiserver.service
index 034c94a0b48..ce073ba884f 100644
--- a/docs/getting-started-guides/coreos/units/apiserver.service
+++ b/docs/getting-started-guides/coreos/units/apiserver.service
@@ -9,6 +9,7 @@ ExecStart=/opt/bin/apiserver \
 --port=8080 \
 --etcd_servers=http://127.0.0.1:4001 \
 --machines=127.0.0.1 \
+--portal_net=10.0.0.0/24 \
 --logtostderr=true
 Restart=on-failure
 RestartSec=1