diff --git a/bin/nova-manage b/bin/nova-manage
index 790e1c0b..ce72c32c 100755
--- a/bin/nova-manage
+++ b/bin/nova-manage
@@ -228,7 +228,7 @@ class ProjectCommands(object):
         ctxt = context.get_admin_context()
         if key:
             if value.lower() == 'unlimited':
-                value = None
+                value = -1
             try:
                 db.quota_update(ctxt, project_id, key, value)
             except exception.ProjectQuotaNotFound: