diff --git a/src/wagtail_factories/blocks.py b/src/wagtail_factories/blocks.py
index 5a78416..3e44758 100644
--- a/src/wagtail_factories/blocks.py
+++ b/src/wagtail_factories/blocks.py
@@ -86,7 +86,7 @@ class StreamFieldFactory(ParameteredAttribute):
 
     """
 
-    def __init__(self, block_types, defaults: Optional[dict]=None):
+    def __init__(self, block_types, defaults: Optional[dict] = None):
         super().__init__(**(defaults or {}))
         if isinstance(block_types, dict):
             # Old style definition, dict mapping block name -> block factory
diff --git a/src/wagtail_factories/factories.py b/src/wagtail_factories/factories.py
index 7b8e681..4f9bd73 100644
--- a/src/wagtail_factories/factories.py
+++ b/src/wagtail_factories/factories.py
@@ -84,7 +84,9 @@ def _get_or_create(cls, model_class, *args, **kwargs):
             if field not in kwargs:
                 raise errors.FactoryError(
                     "django_get_or_create - "
-                    "Unable to find initialization value for '{}' in factory {}".format(field, cls.__name__)
+                    "Unable to find initialization value for '{}' in factory {}".format(
+                        field, cls.__name__
+                    )
                 )
             lookup_fields[field] = kwargs[field]
 
diff --git a/tests/test_stream_block.py b/tests/test_stream_block.py
index ebbcc19..3eddb7c 100644
--- a/tests/test_stream_block.py
+++ b/tests/test_stream_block.py
@@ -81,7 +81,10 @@ def test_page_with_deeply_nested_stream_block_defaults(self):
         assert page.body[0].value["inner_stream"][0].value is None
 
         assert page.body[1].value["inner_stream"][0].block_type == "struct_block"
-        assert page.body[1].value["inner_stream"][0].value["title"] == "lazy function foobar"
+        assert (
+            page.body[1].value["inner_stream"][0].value["title"]
+            == "lazy function foobar"
+        )
 
     def test_page_with_deeply_nested_stream_block_in_list_block(self):
         page = PageWithStreamBlockInListBlockFactory(
@@ -96,7 +99,9 @@ def test_computed_values_on_struct_block_in_nested_stream(self):
         )
         assert page.body[0].value[0].value["boolean"] is True
         assert page.body[0].value[0].value["text"][:4] == "True"
-        assert page.body[0].value[0].value["text"][4:] == str(page.body[0].value[0].value["number"])
+        assert page.body[0].value[0].value["text"][4:] == str(
+            page.body[0].value[0].value["number"]
+        )
 
     def test_factory_with_anonymous_stream_block_in_tree(self):
         # The inner_stream child block is defined as an "anonymous" StreamBlock (i.e. declared