diff --git a/nova/ipv6/account_identifier.py b/nova/ipv6/account_identifier.py
index b23818ee82..a8da65764f 100644
--- a/nova/ipv6/account_identifier.py
+++ b/nova/ipv6/account_identifier.py
@@ -38,15 +38,14 @@ def to_global(prefix, mac, project_id):
     try:
         mac_suffix = netaddr.EUI(mac).value & 0xffffff
         mac_addr = netaddr.IPAddress(mac_suffix)
+    except netaddr.AddrFormatError:
+        raise TypeError(_('Bad mac for to_global_ipv6: %s') % mac)
+
+    try:
         maskIP = netaddr.IPNetwork(prefix).ip
         return (project_hash ^ static_num ^ mac_addr | maskIP).format()
     except netaddr.AddrFormatError:
-        raise TypeError(_('Bad mac for to_global_ipv6: %s') % mac)
-    except TypeError:
         raise TypeError(_('Bad prefix for to_global_ipv6: %s') % prefix)
-    except NameError:
-        raise TypeError(_('Bad project_id for to_global_ipv6: %s') %
-                        project_id)
 
 
 def to_mac(ipv6_address):
diff --git a/nova/ipv6/rfc2462.py b/nova/ipv6/rfc2462.py
index 92746e5a07..9d62f24423 100644
--- a/nova/ipv6/rfc2462.py
+++ b/nova/ipv6/rfc2462.py
@@ -24,15 +24,15 @@ from nova.i18n import _
 
 def to_global(prefix, mac, project_id):
     try:
-        mac64 = netaddr.EUI(mac).eui64().words
-        int_addr = int(''.join(['%02x' % i for i in mac64]), 16)
-        mac64_addr = netaddr.IPAddress(int_addr)
-        maskIP = netaddr.IPNetwork(prefix).ip
-        return (mac64_addr ^ netaddr.IPAddress('::0200:0:0:0') |
-                maskIP).format()
+        mac64 = netaddr.EUI(mac).modified_eui64().value
+        mac64_addr = netaddr.IPAddress(mac64)
     except netaddr.AddrFormatError:
         raise TypeError(_('Bad mac for to_global_ipv6: %s') % mac)
-    except TypeError:
+
+    try:
+        maskIP = netaddr.IPNetwork(prefix).ip
+        return (mac64_addr | maskIP).format()
+    except netaddr.AddrFormatError:
         raise TypeError(_('Bad prefix for to_global_ipv6: %s') % prefix)
 
 
diff --git a/nova/tests/unit/test_ipv6.py b/nova/tests/unit/test_ipv6.py
index 4aa6c2a803..7314d128e7 100644
--- a/nova/tests/unit/test_ipv6.py
+++ b/nova/tests/unit/test_ipv6.py
@@ -35,22 +35,19 @@ class IPv6RFC2462TestCase(test.NoDBTestCase):
 
     def test_to_global_with_bad_mac(self):
         bad_mac = '02:16:3e:33:44:5Z'
-        self.assertRaises(TypeError, ipv6.to_global,
+        expected_msg = 'Bad mac for to_global_ipv6: %s' % bad_mac
+        err = self.assertRaises(TypeError, ipv6.to_global,
                                     '2001:db8::', bad_mac, 'test')
+        self.assertEqual(expected_msg, str(err))
 
     def test_to_global_with_bad_prefix(self):
-        bad_prefix = '82'
-        self.assertRaises(TypeError, ipv6.to_global,
+        bad_prefix = '2001::1::2'
+        expected_msg = 'Bad prefix for to_global_ipv6: %s' % bad_prefix
+        err = self.assertRaises(TypeError, ipv6.to_global,
                                     bad_prefix,
-                                    '2001:db8::216:3eff:fe33:4455',
+                                    '02:16:3e:33:44:55',
                                     'test')
-
-    def test_to_global_with_bad_project(self):
-        bad_project = 'non-existent-project-name'
-        self.assertRaises(TypeError, ipv6.to_global,
-                                    '2001:db8::',
-                                    '2001:db8::a94a:8fe5:ff33:4455',
-                                    bad_project)
+        self.assertEqual(expected_msg, str(err))
 
 
 class IPv6AccountIdentiferTestCase(test.NoDBTestCase):
@@ -69,20 +66,17 @@ class IPv6AccountIdentiferTestCase(test.NoDBTestCase):
         self.assertEqual(mac, '02:16:3e:33:44:55')
 
     def test_to_global_with_bad_mac(self):
-        bad_mac = '02:16:3e:33:44:5X'
-        self.assertRaises(TypeError, ipv6.to_global,
+        bad_mac = '02:16:3e:33:44:5Z'
+        expected_msg = 'Bad mac for to_global_ipv6: %s' % bad_mac
+        err = self.assertRaises(TypeError, ipv6.to_global,
                                     '2001:db8::', bad_mac, 'test')
+        self.assertEqual(expected_msg, str(err))
 
     def test_to_global_with_bad_prefix(self):
-        bad_prefix = '78'
-        self.assertRaises(TypeError, ipv6.to_global,
+        bad_prefix = '2001::1::2'
+        expected_msg = 'Bad prefix for to_global_ipv6: %s' % bad_prefix
+        err = self.assertRaises(TypeError, ipv6.to_global,
                                     bad_prefix,
-                                    '2001:db8::a94a:8fe5:ff33:4455',
+                                    '02:16:3e:33:44:55',
                                     'test')
-
-    def test_to_global_with_bad_project(self):
-        bad_project = 'non-existent-project-name'
-        self.assertRaises(TypeError, ipv6.to_global,
-                                    '2001:db8::',
-                                    '2001:db8::a94a:8fe5:ff33:4455',
-                                    bad_project)
+        self.assertEqual(expected_msg, str(err))