diff --git a/scripts/base/frameworks/cluster/main.zeek b/scripts/base/frameworks/cluster/main.zeek
index 85e1f3a4f9..110f4ad3af 100644
--- a/scripts/base/frameworks/cluster/main.zeek
+++ b/scripts/base/frameworks/cluster/main.zeek
@@ -162,7 +162,8 @@ export {
 		## can specify a particular :rfc:`4007` ``zone_id``.
 		zone_id:      string      &default="";
 		## The port that this node will listen on for peer connections.
-		p:            port        &optional;
+		## A value of ``0/unknown`` means the node is not pre-configured to listen.
+		p:            port        &default=0/unknown;
 		## Identifier for the interface a worker is sniffing.
 		interface:    string      &optional;
 		## Name of the manager node this node uses.  For workers and proxies.
diff --git a/scripts/base/frameworks/cluster/setup-connections.zeek b/scripts/base/frameworks/cluster/setup-connections.zeek
index 7e470037a6..55ab8a460a 100644
--- a/scripts/base/frameworks/cluster/setup-connections.zeek
+++ b/scripts/base/frameworks/cluster/setup-connections.zeek
@@ -89,7 +89,7 @@ event zeek_init() &priority=-10
 	Broker::subscribe(nodeid_topic(Broker::node_id()));
 	Broker::subscribe(node_topic(node));
 
-	if ( self?$p )
+	if ( self$p != 0/unknown )
 		{
 		Broker::listen(Broker::default_listen_address,
 		               self$p,