diff --git a/management/dns_update.py b/management/dns_update.py
index 4ed11157..6b4b5092 100755
--- a/management/dns_update.py
+++ b/management/dns_update.py
@@ -145,7 +145,7 @@ def build_zone(domain, all_domains, additional_records, www_redirect_domains, en
 
 		# Define ns2.PRIMARY_HOSTNAME or whatever the user overrides.
 		# User may provide one or more additional nameservers
-		if get_secondary_dns(additional_records).len > 0:
+		if length(get_secondary_dns(additional_records)) > 0:
 			for secondary_ns in get_secondary_dns(additional_records):
 				records.append((None,  "NS", secondary_ns+'.', False))
 		else: