diff --git a/nova/scheduler/chance.py b/nova/scheduler/chance.py
index f6a289f26..65806d4d5 100644
--- a/nova/scheduler/chance.py
+++ b/nova/scheduler/chance.py
@@ -68,7 +68,7 @@ class ChanceScheduler(driver.Scheduler):
                 host = self._schedule(context, 'compute', request_spec,
                                       filter_properties)
                 updated_instance = driver.instance_update_db(context,
-                        instance_uuid, host)
+                        instance_uuid)
                 self.compute_rpcapi.run_instance(context,
                         instance=updated_instance, host=host,
                         requested_networks=requested_networks,
diff --git a/nova/scheduler/driver.py b/nova/scheduler/driver.py
index a72f3c26d..0ca1d7b89 100644
--- a/nova/scheduler/driver.py
+++ b/nova/scheduler/driver.py
@@ -101,13 +101,13 @@ def cast_to_volume_host(context, host, method, **kwargs):
     LOG.debug(_("Casted '%(method)s' to volume '%(host)s'") % locals())
 
 
-def instance_update_db(context, instance_uuid, host):
-    '''Set the host and scheduled_at fields of an Instance.
+def instance_update_db(context, instance_uuid):
+    '''Clear the host and set the scheduled_at field of an Instance.
 
     :returns: An Instance with the updated fields set properly.
     '''
     now = timeutils.utcnow()
-    values = {'host': host, 'scheduled_at': now}
+    values = {'host': None, 'scheduled_at': now}
     return db.instance_update(context, instance_uuid, values)
 
 
@@ -116,7 +116,7 @@ def cast_to_compute_host(context, host, method, **kwargs):
 
     instance_uuid = kwargs.get('instance_uuid', None)
     if instance_uuid:
-        instance_update_db(context, instance_uuid, host)
+        instance_update_db(context, instance_uuid)
 
     rpc.cast(context,
              rpc.queue_get_for(context, 'compute', host),
diff --git a/nova/scheduler/filter_scheduler.py b/nova/scheduler/filter_scheduler.py
index eddd745db..7b13ab215 100644
--- a/nova/scheduler/filter_scheduler.py
+++ b/nova/scheduler/filter_scheduler.py
@@ -142,8 +142,7 @@ class FilterScheduler(driver.Scheduler):
                         'scheduler.run_instance.scheduled', notifier.INFO,
                         payload)
 
-        updated_instance = driver.instance_update_db(context,
-                instance_uuid, weighted_host.host_state.host)
+        updated_instance = driver.instance_update_db(context, instance_uuid)
 
         self.compute_rpcapi.run_instance(context, instance=updated_instance,
                 host=weighted_host.host_state.host,
diff --git a/nova/tests/scheduler/test_chance_scheduler.py b/nova/tests/scheduler/test_chance_scheduler.py
index 4fb9ab617..26cde055b 100644
--- a/nova/tests/scheduler/test_chance_scheduler.py
+++ b/nova/tests/scheduler/test_chance_scheduler.py
@@ -90,8 +90,8 @@ class ChanceSchedulerTestCase(test_scheduler.SchedulerTestCase):
         self.driver.hosts_up(ctxt_elevated, 'compute').AndReturn(
                 ['host1', 'host2', 'host3', 'host4'])
         random.random().AndReturn(.5)
-        driver.instance_update_db(ctxt, instance1['uuid'],
-                'host3').WithSideEffects(inc_launch_index).AndReturn(instance1)
+        driver.instance_update_db(ctxt, instance1['uuid']).WithSideEffects(
+                inc_launch_index).AndReturn(instance1)
         compute_rpcapi.ComputeAPI.run_instance(ctxt, host='host3',
                 instance=instance1, requested_networks=None,
                 injected_files=None, admin_password=None, is_first_time=None,
@@ -102,8 +102,8 @@ class ChanceSchedulerTestCase(test_scheduler.SchedulerTestCase):
         self.driver.hosts_up(ctxt_elevated, 'compute').AndReturn(
                 ['host1', 'host2', 'host3', 'host4'])
         random.random().AndReturn(.2)
-        driver.instance_update_db(ctxt, instance2['uuid'],
-                'host1').WithSideEffects(inc_launch_index).AndReturn(instance2)
+        driver.instance_update_db(ctxt, instance2['uuid']).WithSideEffects(
+                inc_launch_index).AndReturn(instance2)
         compute_rpcapi.ComputeAPI.run_instance(ctxt, host='host1',
                 instance=instance2, requested_networks=None,
                 injected_files=None, admin_password=None, is_first_time=None,
diff --git a/nova/tests/scheduler/test_scheduler.py b/nova/tests/scheduler/test_scheduler.py
index 83e9cffc8..af297b589 100644
--- a/nova/tests/scheduler/test_scheduler.py
+++ b/nova/tests/scheduler/test_scheduler.py
@@ -712,7 +712,7 @@ class SchedulerDriverModuleTestCase(test.TestCase):
 
         timeutils.utcnow().AndReturn('fake-now')
         db.instance_update(self.context, 'fake_uuid',
-                {'host': host, 'scheduled_at': 'fake-now'})
+                {'host': None, 'scheduled_at': 'fake-now'})
         rpc.queue_get_for(self.context, 'compute', host).AndReturn(queue)
         rpc.cast(self.context, queue,
                 {'method': method,