diff --git a/.gitignore b/.gitignore
index 7947e2f..c94de0a 100644
--- a/.gitignore
+++ b/.gitignore
@@ -6,3 +6,4 @@ bin
 *.py[oc]
 *.pyc
 func-results.json
+.stestr
diff --git a/.zuul.yaml b/.zuul.yaml
index aa9c508..7051aee 100644
--- a/.zuul.yaml
+++ b/.zuul.yaml
@@ -1,4 +1,3 @@
 - project:
     templates:
-      - python-charm-jobs
-      - openstack-python35-jobs-nonvoting
+      - python35-charm-jobs
diff --git a/hooks/cinder_backup_hooks.py b/hooks/cinder_backup_hooks.py
index 083b19e..aa2ac3e 100755
--- a/hooks/cinder_backup_hooks.py
+++ b/hooks/cinder_backup_hooks.py
@@ -1,4 +1,4 @@
-#!/usr/bin/python
+#!/usr/bin/env python3
 #
 # Copyright 2016 Canonical Ltd
 #
diff --git a/hooks/cinder_backup_utils.py b/hooks/cinder_backup_utils.py
index 9621a0f..ce413d4 100644
--- a/hooks/cinder_backup_utils.py
+++ b/hooks/cinder_backup_utils.py
@@ -99,7 +99,7 @@ def restart_map():
                     that should be restarted when file changes.
     """
     _map = []
-    for f, ctxt in CONFIG_FILES.iteritems():
+    for f, ctxt in CONFIG_FILES.items():
         svcs = []
         for svc in ctxt['services']:
             svcs.append(svc)
@@ -111,9 +111,10 @@ def restart_map():
 def set_ceph_env_variables(service):
     # XXX: Horrid kludge to make cinder-backup use
     # a different ceph username than admin
-    env = open('/etc/environment', 'r').read()
+    with open('/etc/environment', 'rt') as f:
+        env = f.read()
     if 'CEPH_ARGS' not in env:
-        with open('/etc/environment', 'a') as out:
+        with open('/etc/environment', 'at') as out:
             out.write('CEPH_ARGS="--id %s"\n' % service)
-    with open('/etc/init/cinder-backup.override', 'w') as out:
+    with open('/etc/init/cinder-backup.override', 'wt') as out:
         out.write('env CEPH_ARGS="--id %s"\n' % service)
diff --git a/tests/basic_deployment.py b/tests/basic_deployment.py
index 29ce31b..d28f784 100644
--- a/tests/basic_deployment.py
+++ b/tests/basic_deployment.py
@@ -745,7 +745,7 @@ class CinderBackupBasicDeployment(OpenStackAmuletDeployment):
             # NOTE(hopem): it appears that at some point cinder-backup stopped
             # restoring volume metadata properly so revert to default name if
             # original is not found
-            name = "restore_backup_%s" % (vol_backup.id)
+            name = "restore_backup_{}".format(vol_backup.id)
             try:
                 cinder_vols = [v for v in vols if v.name == name]
             except AttributeError:
@@ -753,11 +753,11 @@ class CinderBackupBasicDeployment(OpenStackAmuletDeployment):
 
         if not cinder_vols:
             try:
-                msg = ("Could not find restore vol '%s' in %s" %
-                       (name, [v.name for v in vols]))
+                msg = ("Could not find restore vol '{}' in {}"
+                       .format(name, [v.name for v in vols]))
             except AttributeError:
-                msg = ("Could not find restore vol '%s' in %s" %
-                       (name, [v.display_name for v in vols]))
+                msg = ("Could not find restore vol '{}' in {}"
+                       .format(name, [v.display_name for v in vols]))
             u.log.error(msg)
             amulet.raise_status(amulet.FAIL, msg=msg)
 
diff --git a/tox.ini b/tox.ini
index 0b72fa9..1457901 100644
--- a/tox.ini
+++ b/tox.ini
@@ -2,7 +2,7 @@
 # This file is managed centrally by release-tools and should not be modified
 # within individual charm repos.
 [tox]
-envlist = pep8,py27
+envlist = pep8,py3{5,6}
 skipsdist = True
 
 [testenv]
@@ -20,6 +20,7 @@ passenv = HOME TERM AMULET_* CS_API_*
 basepython = python2.7
 deps = -r{toxinidir}/requirements.txt
        -r{toxinidir}/test-requirements.txt
+commands = /bin/true
 
 [testenv:py35]
 basepython = python3.5
diff --git a/unit_tests/__init__.py b/unit_tests/__init__.py
index b7fe4e1..524cb9e 100644
--- a/unit_tests/__init__.py
+++ b/unit_tests/__init__.py
@@ -14,3 +14,4 @@
 
 import sys
 sys.path.append('hooks')
+sys.path.append('unit_tests')
diff --git a/unit_tests/test_utils.py b/unit_tests/test_utils.py
index 74b57c8..a5cf7f7 100644
--- a/unit_tests/test_utils.py
+++ b/unit_tests/test_utils.py
@@ -35,7 +35,7 @@ def load_config():
 
     if not config:
         logging.error('Could not find config.yaml in any parent directory '
-                      'of %s. ' % __file__)
+                      'of %s.'.format(__file__))
         raise Exception
 
     return yaml.safe_load(open(config).read())['options']
@@ -47,7 +47,7 @@ def get_default_config():
     """
     default_config = {}
     config = load_config()
-    for k, v in config.iteritems():
+    for k, v in config.items():
         if 'default' in v:
             default_config[k] = v['default']
         else: