diff --git a/ceph/utils.py b/ceph/utils.py
index ee555e2..e6229c2 100644
--- a/ceph/utils.py
+++ b/ceph/utils.py
@@ -177,7 +177,7 @@ def unmounted_disks():
     for device in context.list_devices(DEVTYPE='disk'):
         if device['SUBSYSTEM'] == 'block':
             matched = False
-            for block_type in [u'dm', u'loop', u'ram', u'nbd']:
+            for block_type in [u'dm-', u'loop', u'ram', u'nbd']:
                 if block_type in device.device_node:
                     matched = True
             if matched:
diff --git a/unit_tests/test_utils.py b/unit_tests/test_utils.py
index f049f71..1ddd7a9 100644
--- a/unit_tests/test_utils.py
+++ b/unit_tests/test_utils.py
@@ -515,14 +515,20 @@ class CephTestCase(unittest.TestCase):
         dev3 = MagicMock(spec=TestDevice)
         dev3.__getitem__.return_value = "block"
         dev3.device_node = '/dev/loop1'
-        devices = [dev1, dev2, dev3]
+        dev4 = MagicMock(spec=TestDevice)
+        dev4.__getitem__.return_value = "block"
+        dev4.device_node = '/dev/sdm'
+        dev5 = MagicMock(spec=TestDevice)
+        dev5.__getitem__.return_value = "block"
+        dev5.device_node = '/dev/dm-1'
+        devices = [dev1, dev2, dev3, dev4, dev5]
         with patch(
                 'pyudev.Context.list_devices',
                 return_value=devices):
             with patch.object(utils, 'is_device_mounted',
                               return_value=False):
                 devices = utils.unmounted_disks()
-                self.assertEqual(devices, ['/dev/sda', '/dev/sdb'])
+                self.assertEqual(devices, ['/dev/sda', '/dev/sdb', '/dev/sdm'])
             with patch.object(utils, 'is_device_mounted',
                               return_value=True):
                 devices = utils.unmounted_disks()