diff --git a/hooks/rabbitmq_server_relations.py b/hooks/rabbitmq_server_relations.py
index 67bd4ccb..0d07318f 100755
--- a/hooks/rabbitmq_server_relations.py
+++ b/hooks/rabbitmq_server_relations.py
@@ -777,7 +777,7 @@ def update_nrpe_checks():
     rabbit.remove_nrpe_files()
 
 
-@hooks.hook('upgrade-charm')
+@hooks.hook('upgrade-charm.real')
 @harden()
 def upgrade_charm():
     pre_install_hooks()
@@ -803,7 +803,9 @@ def upgrade_charm():
         shutil.move(old, new)
 
     rabbit.update_peer_cluster_status()
-    if not rabbit.clustered_with_leader():
+    # this should be run only when rabbitmq is not a single unit and
+    # being really part of a cluster
+    if not rabbit.clustered_with_leader() and config('min-cluster-size'):
         serial = coordinator.Serial()
         log("Requesting cluster join lock")
         serial.acquire(rabbit.COORD_KEY_CLUSTER)