diff --git a/src/cryptography/x509/extensions.py b/src/cryptography/x509/extensions.py
index 938a98e..09d7650 100644
--- a/src/cryptography/x509/extensions.py
+++ b/src/cryptography/x509/extensions.py
@@ -85,7 +85,9 @@
             if isinstance(ext.value, extclass):
                 return ext
 
-        raise ExtensionNotFound("No {0} extension was found".format(extclass), extclass)
+        raise ExtensionNotFound(
+            "No {0} extension was found".format(extclass), extclass
+        )
 
     def __iter__(self):
         return iter(self._extensions)
diff --git a/tests/test_x509_ext.py b/tests/test_x509_ext.py
index a05dc2a..2d3339c 100644
--- a/tests/test_x509_ext.py
+++ b/tests/test_x509_ext.py
@@ -834,7 +834,9 @@
 
     def test_one_extension_get_for_class(self, backend):
         cert = _load_cert(
-            os.path.join("x509", "custom", "basic_constraints_not_critical.pem"),
+            os.path.join(
+                "x509", "custom", "basic_constraints_not_critical.pem"
+            ),
             x509.load_pem_x509_certificate,
             backend
         )
@@ -843,6 +845,7 @@
 
         assert isinstance(ext.value, x509.BasicConstraints)
 
+
 @pytest.mark.requires_backend_interface(interface=RSABackend)
 @pytest.mark.requires_backend_interface(interface=X509Backend)
 class TestBasicConstraintsExtension(object):