diff --git a/.zuul.yaml b/.zuul.yaml
index 059fdee78..690c8c732 100644
--- a/.zuul.yaml
+++ b/.zuul.yaml
@@ -87,6 +87,7 @@
     voting: false
     vars:
       devstack_localrc:
+        USE_PYTHON3: false
         MONASCA_API_IMPLEMENTATION_LANG: python
         MONASCA_PERSISTER_IMPLEMENTATION_LANG: java
         MONASCA_METRICS_DB: influxdb
@@ -97,6 +98,7 @@
     parent: monasca-tempest-base
     vars:
       devstack_localrc:
+        USE_PYTHON3: false
         MONASCA_API_IMPLEMENTATION_LANG: python
         MONASCA_PERSISTER_IMPLEMENTATION_LANG: python
         MONASCA_METRICS_DB: cassandra
@@ -119,6 +121,7 @@
     parent: monasca-tempest-base
     vars:
       devstack_localrc:
+        USE_PYTHON3: false
         MONASCA_API_IMPLEMENTATION_LANG: python
         MONASCA_PERSISTER_IMPLEMENTATION_LANG: java
         MONASCA_METRICS_DB: cassandra
diff --git a/devstack/Vagrantfile b/devstack/Vagrantfile
index 7ac2fe2a0..a233b2867 100644
--- a/devstack/Vagrantfile
+++ b/devstack/Vagrantfile
@@ -170,7 +170,7 @@ MONASCA_METRICS_DB=${MONASCA_METRICS_DB:-influxdb}
 MONASCA_API_USE_MOD_WSGI=${MONASCA_API_USE_MOD_WSGI:-True}
 
 # Start devstack with services running under Python 3
-# USE_PYTHON3=True
+USE_PYTHON3=True
 
 # Uncomment one of the following lines and modify accordingly to enable the Monasca DevStack Plugin
 enable_plugin monasca-api https://git.openstack.org/openstack/monasca-api