diff --git a/p2p/transport/quicreuse/options.go b/p2p/transport/quicreuse/options.go
index 30d07d4443..e87574df76 100644
--- a/p2p/transport/quicreuse/options.go
+++ b/p2p/transport/quicreuse/options.go
@@ -11,7 +11,8 @@ func DisableReuseport() Option {
 	}
 }
 
-// EnableMetrics enables Prometheus metrics collection.
+// EnableMetrics enables Prometheus metrics collection. If reg is nil,
+// prometheus.DefaultRegisterer will be used as the registerer.
 func EnableMetrics(reg prometheus.Registerer) Option {
 	return func(m *ConnManager) error {
 		m.enableMetrics = true