diff --git a/zuul.d/master_jobs.yaml b/zuul.d/master_jobs.yaml
index 9eae70a..73514af 100644
--- a/zuul.d/master_jobs.yaml
+++ b/zuul.d/master_jobs.yaml
@@ -203,6 +203,8 @@
           $NOVA_CONF:
             api:
               dhcp_domain: ''
+            DEFAULT:
+              initial_disk_allocation_ratio: 2.0
         test-config:
           $TEMPEST_CONFIG:
             neutron_plugin_options: