diff --git a/management/ssl_certificates.py b/management/ssl_certificates.py
index 4e84fc07..3e4bbd2a 100755
--- a/management/ssl_certificates.py
+++ b/management/ssl_certificates.py
@@ -266,7 +266,7 @@ def provision_certificates(env, limit_domains):
 		certs[zone] = [[]]
 	for domain in sort_domains(domains, env):
 		# Does the domain end with any domain we've seen so far.
-		for parent in certs.keys():
+		for parent in certs:
 			if domain.endswith("." + parent):
 				# Add this to the parent's list of domains.
 				# Start a new group if the list already has