diff --git a/puppet/zulip_ops/files/nagios4/conf.d/hostgroups.cfg b/puppet/zulip_ops/files/nagios4/conf.d/hostgroups.cfg
index a3d7305263..eb0d28ad38 100644
--- a/puppet/zulip_ops/files/nagios4/conf.d/hostgroups.cfg
+++ b/puppet/zulip_ops/files/nagios4/conf.d/hostgroups.cfg
@@ -55,19 +55,14 @@ define hostgroup {
         alias                   Redis servers
 }
 
-define hostgroup {
-        hostgroup_name          zmirror
-        alias                   Zephyr mirror servers
-}
-
 define hostgroup {
         hostgroup_name          zmirrorp
         alias                   Zephyr mirror personals servers
 }
 
 define hostgroup {
-        hostgroup_name          zmirror_main
-        alias                   Zephyr mirror main servers
+        hostgroup_name          zmirror
+        alias                   Zephyr mirror classes servers
 }
 
 define hostgroup {
diff --git a/puppet/zulip_ops/files/nagios4/conf.d/services.cfg b/puppet/zulip_ops/files/nagios4/conf.d/services.cfg
index 9ce7623290..a3577d38f5 100644
--- a/puppet/zulip_ops/files/nagios4/conf.d/services.cfg
+++ b/puppet/zulip_ops/files/nagios4/conf.d/services.cfg
@@ -152,7 +152,7 @@ define service {
 define service {
         use                             generic-service
         service_description             zephyr mirror forwarding
-        hostgroup_name                  zmirror_main
+        hostgroup_name                  zmirror
         check_command                   check_zephyr_mirror_forwarding!22
         normal_check_interval           2
 # Note: the actual check is run via cron, so retry_check_interval
@@ -165,7 +165,7 @@ define service {
 define service {
         use                             generic-service
         service_description             zmirror subscriptions syncing
-        hostgroup_name                  zmirror_main
+        hostgroup_name                  zmirror
         check_command                   check_sync_public_streams!22
         normal_check_interval           2
         retry_check_interval            2
diff --git a/puppet/zulip_ops/templates/nagios4/hosts.cfg.template.erb b/puppet/zulip_ops/templates/nagios4/hosts.cfg.template.erb
index 31c79a7003..f011986fb2 100644
--- a/puppet/zulip_ops/templates/nagios4/hosts.cfg.template.erb
+++ b/puppet/zulip_ops/templates/nagios4/hosts.cfg.template.erb
@@ -34,7 +34,7 @@ define host{
        host_name        <%= host %>
        alias            <%= host %>
        address          <%= host %>.<%= @default_host_domain %>
-       hostgroups       all,non_aws_host,zmirror,zmirror_main,flaky_servers
+       hostgroups       all,non_aws_host,zmirror,flaky_servers
        }
 <% end -%>
 
@@ -44,7 +44,7 @@ define host{
        host_name        <%= host %>
        alias            <%= host %>
        address          <%= host %>.<%= @default_host_domain %>
-       hostgroups       all,non_aws_host,zmirror,zmirrorp,flaky_servers
+       hostgroups       all,non_aws_host,zmirrorp,flaky_servers
        }
 <% end -%>