diff --git a/thin-provisioning/create_xml_data b/thin-provisioning/create_xml_data
index 42942cb..0168b40 100755
--- a/thin-provisioning/create_xml_data
+++ b/thin-provisioning/create_xml_data
@@ -105,7 +105,7 @@ end
 def xml_metadata(opts, units)
   blocks, to = opts[:thinsize] / opts[:blocksize], 0
 
-  puts begin_superblock(opts[:blocksize], blocks)
+  puts begin_superblock(opts[:blocksize], opts[:thins] * blocks)
   0.step(opts[:thins] - 1) do |devid|
     puts begin_device(devid, opts[:thinsize])
     if opts[:range]