diff --git a/kubetest/objects/__init__.py b/kubetest/objects/__init__.py
index a636334..4ecfac8 100644
--- a/kubetest/objects/__init__.py
+++ b/kubetest/objects/__init__.py
@@ -20,4 +20,4 @@
 from .secret import Secret
 from .service import Service
 from .serviceaccount import ServiceAccount
-from .statefulset import StatefulSet
\ No newline at end of file
+from .statefulset import StatefulSet
diff --git a/kubetest/objects/networkpolicy.py b/kubetest/objects/networkpolicy.py
index ee7d217..c4a0f9a 100644
--- a/kubetest/objects/networkpolicy.py
+++ b/kubetest/objects/networkpolicy.py
@@ -25,9 +25,9 @@ class NetworkPolicy(ApiObject):
     obj_type = client.V1NetworkPolicy
 
     api_clients = {
-            'preffered': client.NetworkingV1Api,
-            'networking.k8s.io/v1': client.NetworkingV1Api,
-            }
+        'preffered': client.NetworkingV1Api,
+        'networking.k8s.io/v1': client.NetworkingV1Api,
+    }
 
     def __str__(self):
         return str(self.obj)
@@ -48,16 +48,16 @@ def create(self, namespace: str = None) -> None:
             namespace = self.namespace
 
         log.info(
-                'creating networkpolicy "%s" in namespace "%s"',
-                self.name,
-                self.namespace
-                )
+            'creating networkpolicy "%s" in namespace "%s"',
+            self.name,
+            self.namespace
+        )
         log.debug('network_policy: %s', self.obj)
 
         self.obj = self.api_client.create_namespaced_network_policy(
-                namespace=namespace,
-                body=self.obj,
-                )
+            namespace=namespace,
+            body=self.obj,
+        )
 
     def delete(self, options: client.V1DeleteOptions = None) -> client.V1Status:
         """Delete the NetworkPolicy.
@@ -80,17 +80,17 @@ def delete(self, options: client.V1DeleteOptions = None) -> client.V1Status:
         log.debug('network_policy: %s', self.obj)
 
         return self.api_client.delete_namespaced_network_policy(
-                name=self.name,
-                namespace=self.namespace,
-                body=options,
-                )
+            name=self.name,
+            namespace=self.namespace,
+            body=options,
+        )
 
     def refresh(self) -> None:
         """Refresh the underlying Kubernetes NetworkPolicy resource."""
         self.obj = self.api_client.read_namespaced_network_policy(
-                name=self.name,
-                namespace=self.namespace,
-                )
+            name=self.name,
+            namespace=self.namespace,
+        )
 
     def is_ready(self) -> None:
         """Check if the NetworkPolicy is in the ready state.
diff --git a/kubetest/plugin.py b/kubetest/plugin.py
index 239b020..36ed2df 100644
--- a/kubetest/plugin.py
+++ b/kubetest/plugin.py
@@ -8,13 +8,12 @@
 import logging
 import os
 import warnings
+from typing import Optional
 
 import kubernetes
 import pytest
 import urllib3
 
-from typing import Optional
-
 from kubetest import errors, markers
 from kubetest.client import TestClient
 from kubetest.manager import KubetestManager
@@ -434,14 +433,15 @@ def kubeconfig(request) -> Optional[str]:
 
 @pytest.fixture
 def kubecontext(request) -> Optional[str]:
-    """Return the context in the kubeconfig to use for the tests. 
-    
+    """Return the context in the kubeconfig to use for the tests.
+
     When None, use the current context as set in the kubeconfig.
     """
 
     context = request.session.config.getoption('kube_context')
     return context
 
+
 @pytest.fixture()
 def kube(kubeconfig, kubecontext, request) -> TestClient:
     """Return a client for managing a Kubernetes cluster for testing."""
diff --git a/tests/conftest.py b/tests/conftest.py
index f91f2ce..2a8975a 100644
--- a/tests/conftest.py
+++ b/tests/conftest.py
@@ -275,5 +275,5 @@ def simple_networkpolicy():
         spec=client.V1NetworkPolicySpec(
             pod_selector=client.V1LabelSelector(),
             policy_types=["Egress", "Ingress"],
-            )
+        )
     )
diff --git a/tox.ini b/tox.ini
index 40180ff..8a6e04d 100644
--- a/tox.ini
+++ b/tox.ini
@@ -72,6 +72,7 @@ commands=
 [testenv:format]
 description=
     run basic formatting tools against the source code
+basepython=python3
 deps=
     isort>=5.0.0
     autopep8