diff --git a/doc/authentication.dox b/doc/authentication.dox
index ec6f1936..fd76d71e 100644
--- a/doc/authentication.dox
+++ b/doc/authentication.dox
@@ -63,7 +63,7 @@ int authenticate_pubkey(ssh_session session)
 {
   int rc;
 
-  rc = ssh_userauth_publickey_auto(session, NULL);
+  rc = ssh_userauth_publickey_auto(session, NULL, NULL);
 
   if (rc == SSH_AUTH_ERROR)
   {