diff --git a/nixops/backends/ec2.py b/nixops/backends/ec2.py
index 9d0204831..8cb88c8a9 100644
--- a/nixops/backends/ec2.py
+++ b/nixops/backends/ec2.py
@@ -600,8 +600,9 @@ def _assign_elastic_ip(self, elastic_ipv4, check):
     def security_groups_to_ids(self, subnetId, groups):
         sg_names = filter(lambda g: not g.startswith('sg-'), groups)
         if sg_names != [ ] and subnetId != "":
-            self.connect_vpc()
-            vpc_id = self._conn_vpc.get_all_subnets([subnetId])[0].vpc_id
+            self.connect()
+            subnet_id_filter = {'Name': 'subnet-id', 'Values': [vpc_id]}
+            vpc_id = [vpc.vpc_id for vpc in self._conn.subnets.filter(Filters=[subnet_id_filter]).limit(1)][0]
             groups = map(lambda g: nixops.ec2_utils.name_to_security_group(self._conn, g, vpc_id), groups)
 
         return groups