diff --git a/horizon/server/single.yml b/horizon/server/single.yml
index 73fbcc3..79783cc 100644
--- a/horizon/server/single.yml
+++ b/horizon/server/single.yml
@@ -1,5 +1,6 @@
 classes:
 - service.horizon.server.single
+- system.horizon.upgrade
 - system.horizon.server.iptables
 - system.apache.server.single
 - system.memcached.server.single