diff --git a/zuul.d/train_jobs.yaml b/zuul.d/train_jobs.yaml
index 961b3b7..c8c2efe 100644
--- a/zuul.d/train_jobs.yaml
+++ b/zuul.d/train_jobs.yaml
@@ -25,6 +25,7 @@
         q-meta: true
         q-metering: true
       branch_override: stable/train
+      tempest_concurrency: 4
       tempest_test_regex: ^neutron_tempest_plugin\.api
       # TODO(slaweq): find a way to put this list of extensions in
       # neutron repository and keep it different per branch,