diff --git a/qubesadmin/tools/qvm_ls.py b/qubesadmin/tools/qvm_ls.py
index f041e1d..4e672a9 100644
--- a/qubesadmin/tools/qvm_ls.py
+++ b/qubesadmin/tools/qvm_ls.py
@@ -325,7 +325,7 @@ def calc_used(vm, volume_name):
     if size == 0:
         return 0
     usage = calc_usage(vm, volume_name)
-    return usage * 100 // size
+    return '{}%'.format(usage * 100 // size)
 
 
 # todo maxmem