diff --git a/ansible/roles/horizon/tasks/start.yml b/ansible/roles/horizon/tasks/start.yml
index e50e57c16c..84cefb35b2 100644
--- a/ansible/roles/horizon/tasks/start.yml
+++ b/ansible/roles/horizon/tasks/start.yml
@@ -10,6 +10,7 @@
       ENABLE_DESIGNATE: "{{ 'yes' if enable_designate | bool else 'no' }}"
       ENABLE_IRONIC: "{{ 'yes' if enable_ironic | bool else 'no' }}"
       ENABLE_MANILA: "{{ 'yes' if  enable_manila | bool else 'no' }}"
+      ENABLE_MISTRAL: "{{ 'yes' if  enable_mistral | bool else 'no' }}"
       ENABLE_NEUTRON_LBAAS: "{{ 'yes' if  enable_neutron_lbaas | bool else 'no' }}"
       ENABLE_SAHARA: "{{ 'yes' if enable_sahara | bool else 'no' }}"
       ENABLE_SEARCHLIGHT: "{{ 'yes' if enable_searchlight | bool else 'no' }}"