diff --git a/scripts/base/frameworks/cluster/main.zeek b/scripts/base/frameworks/cluster/main.zeek
index d73093a8cf..3ac6ab0c7d 100644
--- a/scripts/base/frameworks/cluster/main.zeek
+++ b/scripts/base/frameworks/cluster/main.zeek
@@ -56,12 +56,10 @@ export {
 	## relevant to all nodes in a cluster. Currently, there is not a common
 	## topic to broadcast to, because enabling implicit Broker forwarding would
 	## cause a routing loop for this topic.
-	const broadcast_topics = {
-		logger_topic,
-		manager_topic,
-		proxy_topic,
-		worker_topic,
-	};
+	##
+	## Note that with :zeek:see:`Cluster::enable_global_pub_sub` and non-Broker
+	## backends a single broadcast topic has become an option.
+	const broadcast_topics: set[string] = set() &ordered;
 
 	## The topic prefix used for exchanging messages that are relevant to
 	## a named node in a cluster.  Used with broker-enabled cluster communication.
@@ -552,6 +550,13 @@ event node_down(name: string, id: string) &priority=10
 		                    name, id));
 	}
 
+event zeek_init() &priority=1000
+	{
+	# Populate broadcast_topics based on redef'ble consts.
+	for ( _, topic in vector(manager_topic, logger_topic, worker_topic, proxy_topic) )
+		add broadcast_topics[topic];
+	}
+
 event zeek_init() &priority=5
 	{
 	# If a node is given, but it's an unknown name we need to fail.