diff --git a/oslo_utils/imageutils.py b/oslo_utils/imageutils.py
index c63314a4..b829abd6 100644
--- a/oslo_utils/imageutils.py
+++ b/oslo_utils/imageutils.py
@@ -92,7 +92,7 @@ class QemuImgInfo(object):
                 real_details = backing_match.group(2).strip()
         elif root_cmd in ['virtual_size', 'cluster_size', 'disk_size']:
             # Replace it with the byte amount (if we can convert it)
-            if root_details == 'None':
+            if root_details in ('None', 'unavailable'):
                 real_details = 0
             else:
                 real_details = self._extract_bytes(root_details)
diff --git a/oslo_utils/tests/test_imageutils.py b/oslo_utils/tests/test_imageutils.py
index cb8b356d..5c328fe4 100644
--- a/oslo_utils/tests/test_imageutils.py
+++ b/oslo_utils/tests/test_imageutils.py
@@ -51,10 +51,12 @@ class ImageUtilsRawTestCase(test_base.BaseTestCase):
     _disk_size = [
         ('96K', dict(disk_size='96K',
                      exp_disk_size=98304)),
-        ('96K_byte', dict(disk_size='963434',
-                          exp_disk_size=963434)),
-        ('3.1M', dict(disk_size='3.1G',
+        ('96K_byte', dict(disk_size='98304',
+                          exp_disk_size=98304)),
+        ('3.1G', dict(disk_size='3.1G',
                       exp_disk_size=3328599655)),
+        ('unavailable', dict(disk_size='unavailable',
+                             exp_disk_size=0)),
     ]
 
     _garbage_before_snapshot = [