diff --git a/src/java/org/apache/cassandra/gms/Gossiper.java b/src/java/org/apache/cassandra/gms/Gossiper.java
index 3d6414913f..8fe8044547 100644
--- a/src/java/org/apache/cassandra/gms/Gossiper.java
+++ b/src/java/org/apache/cassandra/gms/Gossiper.java
@@ -2234,7 +2234,9 @@ public class Gossiper implements IFailureDetectionEventListener, GossiperMBean,
     {
         checkProperThreadForStateMutation();
         assert !endpoint.equals(getBroadcastAddressAndPort()) || epstate.getHeartBeatState().getGeneration() > 0 :
-        "We should not update epstates with generation = 0 for the local host";
+        String.format("We should not update epstates with generation = 0 for the local host " +
+                      "(endpoint: %s, broadcast: %s, generation: %s)",
+                      endpoint, getBroadcastAddressAndPort(), epstate.getHeartBeatState().getGeneration());
         EndpointState old = endpointStateMap.get(endpoint);
         if (old == null)
             endpointStateMap.put(endpoint, epstate);
diff --git a/src/java/org/apache/cassandra/tcm/listeners/UpgradeMigrationListener.java b/src/java/org/apache/cassandra/tcm/listeners/UpgradeMigrationListener.java
index feb191d32a..5d7e787796 100644
--- a/src/java/org/apache/cassandra/tcm/listeners/UpgradeMigrationListener.java
+++ b/src/java/org/apache/cassandra/tcm/listeners/UpgradeMigrationListener.java
@@ -47,17 +47,23 @@ public class UpgradeMigrationListener implements ChangeListener
             logger.info("Detected upgrade from gossip mode");
             return;
         }
-        else if (prev.epoch.equals(Epoch.FIRST) && !next.directory.isEmpty()) // directory is non-empty after initialization during gossip upgrade
+        else if (prev.epoch.equals(Epoch.FIRST) && !next.directory.isEmpty())
         {
             NodeId localId = next.myNodeId();
             if (localId != null)
             {
-                logger.info("Initialized CMS, updating local host id to {}", next.myNodeId());
-                SystemKeyspace.setLocalHostId(next.myNodeId().toUUID());
-                Gossiper.instance.mergeNodeToGossip(next.myNodeId(), next);
+                // assigning the local node id is done in Epoch.FIRST in one of two scenarios:
+                // * during an upgrade from gossip, as all pre-existing nodes will have an id assigned
+                // * during CMS initialization for a brand new cluster iff the local node is the first CMS member
+                logger.info("Initialized CMS, updating local host id to {}", localId);
+                SystemKeyspace.setLocalHostId(localId.toUUID());
+                if (Gossiper.instance.isEnabled())
+                {
+                    Gossiper.instance.mergeNodeToGossip(localId, next);
+                    if (Gossiper.instance.getQuarantineDisabled())
+                        Gossiper.instance.clearQuarantinedEndpoints();
+                }
             }
-            if (Gossiper.instance.getQuarantineDisabled())
-                Gossiper.instance.clearQuarantinedEndpoints();
         }
 
         CassandraVersion prevMinVersion = prev.directory.clusterMinVersion.cassandraVersion;