diff --git a/contrib/inventory_builder/tests/test_inventory.py b/contrib/inventory_builder/tests/test_inventory.py
index aa03e7c6409..1172406ea94 100644
--- a/contrib/inventory_builder/tests/test_inventory.py
+++ b/contrib/inventory_builder/tests/test_inventory.py
@@ -51,7 +51,7 @@ def test_ensure_required_groups(self):
         groups = ['group1', 'group2']
         self.inv.ensure_required_groups(groups)
         for group in groups:
-            self.assertTrue(group in self.inv.yaml_config['all']['children'])
+            self.assertIn(group, self.inv.yaml_config['all']['children'])
 
     def test_get_host_id(self):
         hostnames = ['node99', 'no99de01', '01node01', 'node1.domain',
@@ -227,8 +227,9 @@ def test_set_kube_master(self):
         host = 'node1'
 
         self.inv.set_kube_master([host])
-        self.assertTrue(
-            host in self.inv.yaml_config['all']['children'][group]['hosts'])
+        self.assertIn(
+            host,
+            self.inv.yaml_config['all']['children'][group]['hosts'])
 
     def test_set_all(self):
         hosts = OrderedDict([
@@ -246,8 +247,8 @@ def test_set_k8s_cluster(self):
 
         self.inv.set_k8s_cluster()
         for host in expected_hosts:
-            self.assertTrue(
-                host in
+            self.assertIn(
+                host,
                 self.inv.yaml_config['all']['children'][group]['children'])
 
     def test_set_kube_node(self):
@@ -255,16 +256,18 @@ def test_set_kube_node(self):
         host = 'node1'
 
         self.inv.set_kube_node([host])
-        self.assertTrue(
-            host in self.inv.yaml_config['all']['children'][group]['hosts'])
+        self.assertIn(
+            host,
+            self.inv.yaml_config['all']['children'][group]['hosts'])
 
     def test_set_etcd(self):
         group = 'etcd'
         host = 'node1'
 
         self.inv.set_etcd([host])
-        self.assertTrue(
-            host in self.inv.yaml_config['all']['children'][group]['hosts'])
+        self.assertIn(
+            host,
+            self.inv.yaml_config['all']['children'][group]['hosts'])
 
     def test_scale_scenario_one(self):
         num_nodes = 50
diff --git a/contrib/inventory_builder/tox.ini b/contrib/inventory_builder/tox.ini
index 889fe78537f..125f6463e33 100644
--- a/contrib/inventory_builder/tox.ini
+++ b/contrib/inventory_builder/tox.ini
@@ -1,7 +1,7 @@
 [tox]
 minversion = 1.6
 skipsdist = True
-envlist = pep8, py33
+envlist = pep8, py3
 
 [testenv]
 whitelist_externals = py.test