diff --git a/src/certificate.py b/src/certificate.py
index 5ca29ce55..299095af0 100644
--- a/src/certificate.py
+++ b/src/certificate.py
@@ -798,7 +798,7 @@ def _check_domain_is_ready_for_ACME(domain):
         or {}
     )
 
-    parent_domain = _get_parent_domain_of(domain)
+    parent_domain = _get_parent_domain_of(domain, return_self=True)
 
     dnsrecords = (
         Diagnoser.get_cached_report(