diff --git a/nova/tests/unit/virt/libvirt/test_driver.py b/nova/tests/unit/virt/libvirt/test_driver.py
index 486bff1f2fa2..c4f89f16e6ce 100644
--- a/nova/tests/unit/virt/libvirt/test_driver.py
+++ b/nova/tests/unit/virt/libvirt/test_driver.py
@@ -6643,6 +6643,21 @@ class LibvirtConnTestCase(test.NoDBTestCase):
                           self.context, instance_ref, 'dest',
                           False, None, dom)
 
+    def test_live_migration_fails_with_invalid_live_migration_flag(self):
+        self.flags(live_migration_flag="VIR_MIGRATE_UNDEFINE_SOURCE, "
+                                       "VIR_MIGRATE_PEER2PEER, "
+                                       "VIR_MIGRATE_LIVE, "
+                                       "VIR_MIGRATE_TUNNELLED, "
+                                       "VIR_MIGRATE_FOO_BAR",
+                   group='libvirt')
+        instance_ref = self.test_instance
+        dom = fakelibvirt.virDomain
+        drvr = libvirt_driver.LibvirtDriver(fake.FakeVirtAPI(), False)
+        self.assertRaises(exception.Invalid,
+                          drvr._live_migration_operation,
+                          self.context, instance_ref, 'dest',
+                          False, None, dom)
+
     @mock.patch.object(fakelibvirt, 'VIR_DOMAIN_XML_MIGRATABLE', None,
                        create=True)
     def test_live_migration_uses_migrateToURI_without_migratable_flag(self):
diff --git a/nova/virt/libvirt/driver.py b/nova/virt/libvirt/driver.py
index b9eecd296e74..b1a873f3022f 100644
--- a/nova/virt/libvirt/driver.py
+++ b/nova/virt/libvirt/driver.py
@@ -5666,7 +5666,15 @@ class LibvirtDriver(driver.ComputeDriver):
                 flaglist = CONF.libvirt.block_migration_flag.split(',')
             else:
                 flaglist = CONF.libvirt.live_migration_flag.split(',')
-            flagvals = [getattr(libvirt, x.strip()) for x in flaglist]
+
+            def getflag(s):
+                try:
+                    return getattr(libvirt, s)
+                except AttributeError:
+                    msg = _("Unknown libvirt live migration flag '%s'") % s
+                    raise exception.Invalid(msg)
+
+            flagvals = [getflag(x.strip()) for x in flaglist]
             logical_sum = six.moves.reduce(lambda x, y: x | y, flagvals)
 
             pre_live_migrate_data = (migrate_data or {}).get(