diff --git a/certbot_dns_ionos/dns_ionos.py b/certbot_dns_ionos/dns_ionos.py
index 697bb68..a7f3f3e 100644
--- a/certbot_dns_ionos/dns_ionos.py
+++ b/certbot_dns_ionos/dns_ionos.py
@@ -97,7 +97,7 @@ class _ionosClient(object):
         # is a subdomain
         for zone in zones:
             # get the zone id
-            if domain.endswith(zone['name']):
+            if domain.endswith(f".{zone['name']}"):
                 return zone['id'], zone['name']
         return None, None