diff --git a/qubes/storage/__init__.py b/qubes/storage/__init__.py
index 4d04a818..e0257491 100644
--- a/qubes/storage/__init__.py
+++ b/qubes/storage/__init__.py
@@ -96,7 +96,7 @@ class Volume(object):
         self.revisions_to_keep = revisions_to_keep
         self.rw = rw
         self.save_on_stop = save_on_stop
-        self.size = int(size)
+        self._size = int(size)
         self.snap_on_start = snap_on_start
         self.source = source
         self.vid = vid
@@ -133,6 +133,10 @@ class Volume(object):
         msg = "{!s} has revisions not implemented".format(self.__class__)
         raise NotImplementedError(msg)
 
+    @property
+    def size(self):
+        return self._size
+
     @property
     def config(self):
         ''' return config data for serialization to qubes.xml '''