diff --git a/common/block_add_change b/common/block_add_change
index b4bd0f03..e76235ec 100755
--- a/common/block_add_change
+++ b/common/block_add_change
@@ -2,7 +2,7 @@
 
 NAME=${DEVNAME#/dev/}
 DESC="${ID_MODEL} (${ID_FS_LABEL})"
-SIZE=$(cat /sys/$DEVPATH/size)
+SIZE=$[ $(cat /sys/$DEVPATH/size) * 512 ]
 MODE=w
 XS_KEY="qubes-block-devices/$NAME"
 
diff --git a/dom0/qvm-tools/qvm-block b/dom0/qvm-tools/qvm-block
index c16c6905..66f416f2 100755
--- a/dom0/qvm-tools/qvm-block
+++ b/dom0/qvm-tools/qvm-block
@@ -107,7 +107,7 @@ def main():
             attached_to_str = ""
             if attached_to:
                 attached_to_str = " (attached to '%s' as '%s')" % (attached_to['vm'], attached_to['frontend'])
-            size_str = kbytes_to_kmg(dev['size'])
+            size_str = bytes_to_kmg(dev['size'])
             print "%s\t%s %s%s" % (dev['name'], dev['desc'], size_str, attached_to_str)
         exit (0)