diff --git a/challenge/dnspersist01/client_zone.go b/challenge/dnspersist01/client_zone.go
index 455258f0d..7c2c3ff8c 100644
--- a/challenge/dnspersist01/client_zone.go
+++ b/challenge/dnspersist01/client_zone.go
@@ -43,7 +43,7 @@ func (c *Client) fetchSoaByFqdn(ctx context.Context, fqdn string, nameservers []
 		r   *dns.Msg
 	)
 
-	for domain := range DomainsSeq(fqdn) {
+	for domain := range domainsSeq(fqdn) {
 		r, err = c.sendQueryCustom(ctx, domain, dns.TypeSOA, nameservers, true)
 		if err != nil {
 			continue
diff --git a/challenge/dnspersist01/fqdn.go b/challenge/dnspersist01/fqdn.go
index 9ced86ce6..f4ae781be 100644
--- a/challenge/dnspersist01/fqdn.go
+++ b/challenge/dnspersist01/fqdn.go
@@ -11,8 +11,8 @@ import (
  * The 2 files should be kept in sync.
  */
 
-// DomainsSeq generates a sequence of domain names derived from a domain (FQDN or not) in descending order.
-func DomainsSeq(fqdn string) iter.Seq[string] {
+// domainsSeq generates a sequence of domain names derived from a domain (FQDN or not) in descending order.
+func domainsSeq(fqdn string) iter.Seq[string] {
 	return func(yield func(string) bool) {
 		if fqdn == "" {
 			return