diff --git a/nova/tests/unit/virt/hyperv/test_block_device_manager.py b/nova/tests/unit/virt/hyperv/test_block_device_manager.py
index 939666e87b71..cfeb6698f414 100644
--- a/nova/tests/unit/virt/hyperv/test_block_device_manager.py
+++ b/nova/tests/unit/virt/hyperv/test_block_device_manager.py
@@ -216,6 +216,9 @@ class BlockDeviceManagerTestCase(test_base.HyperVBaseTestCase):
     def test_check_and_update_root_device_gen1(self):
         self._test_check_and_update_root_device(disk_format='vhd')
 
+    def test_check_and_update_root_device_gen1_vhdx(self):
+        self._test_check_and_update_root_device(disk_format='vhdx')
+
     def test_check_and_update_root_device_gen1_iso(self):
         self._test_check_and_update_root_device(disk_format='iso')
 
diff --git a/nova/virt/hyperv/block_device_manager.py b/nova/virt/hyperv/block_device_manager.py
index 3f2ff7d3fee8..9323da09f547 100644
--- a/nova/virt/hyperv/block_device_manager.py
+++ b/nova/virt/hyperv/block_device_manager.py
@@ -41,6 +41,7 @@ class BlockDeviceInfoManager(object):
     _DEFAULT_BUS = constants.CTRL_TYPE_SCSI
 
     _TYPE_FOR_DISK_FORMAT = {'vhd': constants.DISK,
+                             'vhdx': constants.DISK,
                              'iso': constants.DVD}
 
     _DEFAULT_ROOT_DEVICE = '/dev/sda'