diff --git a/nova/api/ec2/cloud.py b/nova/api/ec2/cloud.py
index 57d41ed67be6..c94540793405 100644
--- a/nova/api/ec2/cloud.py
+++ b/nova/api/ec2/cloud.py
@@ -729,7 +729,7 @@ class CloudController(object):
             ec2_id = None
             if (floating_ip_ref['fixed_ip']
                 and floating_ip_ref['fixed_ip']['instance']):
-                instance_id = floating_ip_ref['fixed_ip']['instance']['ec2_id']
+                instance_id = floating_ip_ref['fixed_ip']['instance']['id']
                 ec2_id = id_to_ec2_id(instance_id)
             address_rv = {'public_ip': address,
                           'instance_id': ec2_id}