diff --git a/nova/scheduler/host_manager.py b/nova/scheduler/host_manager.py
index 43d7db9e6104..3ef1547f48b0 100644
--- a/nova/scheduler/host_manager.py
+++ b/nova/scheduler/host_manager.py
@@ -183,16 +183,16 @@ class HostState(object):
         all_ram_mb = compute['memory_mb']
 
         # Assume virtual size is all consumed by instances if use qcow2 disk.
-        free_gb = compute.get('free_disk_gb')
+        free_gb = compute['free_disk_gb']
         least_gb = compute.get('disk_available_least')
-        if least_gb > free_gb and free_gb:
-            # can occur when an instance in database is not on host
-            LOG.warn(_("Host has more disk space than database expected"
-                       " (%(physical)sgb > %(database)sgb)") %
-                     {'physical': least_gb, 'database': free_gb})
-        free_disk_mb = min(val for val in [least_gb,
-                                           free_gb] if val is not None)
-        free_disk_mb *= 1024
+        if least_gb is not None:
+            if least_gb > free_gb:
+                # can occur when an instance in database is not on host
+                LOG.warn(_("Host has more disk space than database expected"
+                           " (%(physical)sgb > %(database)sgb)") %
+                         {'physical': least_gb, 'database': free_gb})
+            free_gb = min(least_gb, free_gb)
+        free_disk_mb = free_gb * 1024
 
         self.disk_mb_used = compute['local_gb_used'] * 1024
 
diff --git a/nova/tests/scheduler/fakes.py b/nova/tests/scheduler/fakes.py
index 6cb91a9f55f4..ee89e1d7d3d8 100644
--- a/nova/tests/scheduler/fakes.py
+++ b/nova/tests/scheduler/fakes.py
@@ -34,7 +34,7 @@ COMPUTE_NODES = [
              hypervisor_version=0),
         dict(id=2, local_gb=2048, memory_mb=2048, vcpus=2,
              disk_available_least=1024, free_ram_mb=1024, vcpus_used=2,
-             free_disk_gb=None, local_gb_used=0, updated_at=None,
+             free_disk_gb=1024, local_gb_used=0, updated_at=None,
              service=dict(host='host2', disabled=True),
              hypervisor_hostname='node2', host_ip='127.0.0.1',
              hypervisor_version=0),
@@ -57,7 +57,7 @@ COMPUTE_NODES = [
 COMPUTE_NODES_METRICS = [
         dict(id=1, local_gb=1024, memory_mb=1024, vcpus=1,
              disk_available_least=512, free_ram_mb=512, vcpus_used=1,
-             free_disk_mb=512, local_gb_used=0, updated_at=None,
+             free_disk_gb=512, local_gb_used=0, updated_at=None,
              service=dict(host='host1', disabled=False),
              hypervisor_hostname='node1', host_ip='127.0.0.1',
              hypervisor_version=0,
@@ -74,7 +74,7 @@ COMPUTE_NODES_METRICS = [
                                      ])),
         dict(id=2, local_gb=2048, memory_mb=2048, vcpus=2,
              disk_available_least=1024, free_ram_mb=1024, vcpus_used=2,
-             free_disk_mb=1024, local_gb_used=0, updated_at=None,
+             free_disk_gb=1024, local_gb_used=0, updated_at=None,
              service=dict(host='host2', disabled=True),
              hypervisor_hostname='node2', host_ip='127.0.0.1',
              hypervisor_version=0,
@@ -91,7 +91,7 @@ COMPUTE_NODES_METRICS = [
                                      ])),
         dict(id=3, local_gb=4096, memory_mb=4096, vcpus=4,
              disk_available_least=3072, free_ram_mb=3072, vcpus_used=1,
-             free_disk_mb=3072, local_gb_used=0, updated_at=None,
+             free_disk_gb=3072, local_gb_used=0, updated_at=None,
              service=dict(host='host3', disabled=False),
              hypervisor_hostname='node3', host_ip='127.0.0.1',
              hypervisor_version=0,
@@ -108,7 +108,7 @@ COMPUTE_NODES_METRICS = [
                                      ])),
         dict(id=4, local_gb=8192, memory_mb=8192, vcpus=8,
              disk_available_least=8192, free_ram_mb=8192, vcpus_used=0,
-             free_disk_mb=8192, local_gb_used=0, updated_at=None,
+             free_disk_gb=8192, local_gb_used=0, updated_at=None,
              service=dict(host='host4', disabled=False),
              hypervisor_hostname='node4', host_ip='127.0.0.1',
              hypervisor_version=0,