diff --git a/dns_scripts/dns_route53.py b/dns_scripts/dns_route53.py
index 8805269..a972dfa 100755
--- a/dns_scripts/dns_route53.py
+++ b/dns_scripts/dns_route53.py
@@ -32,7 +32,7 @@ for zone in response['HostedZones']:
         zone_list[zone['Name']] = zone['Id']
 
 for key in sorted(zone_list.iterkeys(), key=len, reverse=True):
-    if key in "{z}.".format(z=fqdn):
+    if ".{z}".format(z=key) in ".{z}.".format(z=fqdn):
        zone_id = zone_list[key]
 
 if zone_id == "":
@@ -84,4 +84,4 @@ if action == 'UPSERT':
             print("Didn't find {f} entry yet, sleeping... ({w}s)".format(f=challenge_fqdn,
                                                                          w=waiting))
             time.sleep(10)
-            pass
\ No newline at end of file
+            pass