diff --git a/qvm-tools/qvm-backup b/qvm-tools/qvm-backup
index 6f96a97d..601bd009 100755
--- a/qvm-tools/qvm-backup
+++ b/qvm-tools/qvm-backup
@@ -22,7 +22,7 @@
 
 from qubes.qubes import QubesVmCollection
 from qubes.qubes import QubesException
-from qubes.qubesutils import backup_prepare, backup_do_copy
+from qubes.qubesutils import backup_prepare, backup_do_copy, size_to_human
 from optparse import OptionParser
 import os
 import sys