diff --git a/fimfarchive/converters/fpub_epub.py b/fimfarchive/converters/fpub_epub.py
index 3e78c85..4f00dcd 100644
--- a/fimfarchive/converters/fpub_epub.py
+++ b/fimfarchive/converters/fpub_epub.py
@@ -77,7 +77,7 @@ class FpubEpubConverter(Converter):
     Converts story data from FPUB to EPUB.
     """
 
-    def __init__(self, logdir: Union[Path, str] = None) -> None:
+    def __init__(self, logdir: Union[None, Path, str] = None) -> None:
         self.logdir = get_path(logdir)
 
         if self.logdir and not self.logdir.is_dir():
diff --git a/fimfarchive/fetchers/directory.py b/fimfarchive/fetchers/directory.py
index f21da27..24baf84 100644
--- a/fimfarchive/fetchers/directory.py
+++ b/fimfarchive/fetchers/directory.py
@@ -49,8 +49,8 @@ class DirectoryFetcher(Iterable[Story], Sized, Fetcher):
 
     def __init__(
             self,
-            meta_path: Union[Path, str] = None,
-            data_path: Union[Path, str] = None,
+            meta_path: Union[None, Path, str] = None,
+            data_path: Union[None, Path, str] = None,
             flavors: Iterable[Flavor] = tuple(),
             ) -> None:
         """
diff --git a/fimfarchive/mappers.py b/fimfarchive/mappers.py
index eb4ab5b..3505c17 100644
--- a/fimfarchive/mappers.py
+++ b/fimfarchive/mappers.py
@@ -134,7 +134,7 @@ class StorySlugMapper(Mapper[str]):
     Returns a slug-based file path for a story.
     """
 
-    def __init__(self, template: str = None) -> None:
+    def __init__(self, template: Optional[str] = None) -> None:
         """
         Constructor.
 
diff --git a/fimfarchive/stories.py b/fimfarchive/stories.py
index 7d80b27..58c5bad 100644
--- a/fimfarchive/stories.py
+++ b/fimfarchive/stories.py
@@ -22,7 +22,7 @@ Stories for Fimfarchive.
 #
 
 
-from typing import TYPE_CHECKING, Any, Dict, Iterable, TypeVar
+from typing import TYPE_CHECKING, Any, Dict, Iterable, Optional, TypeVar
 
 from fimfarchive.exceptions import StorySourceError
 
@@ -48,9 +48,9 @@ class Story:
     def __init__(
             self,
             key: int,
-            fetcher: Fetcher = None,
-            meta: Dict[str, Any] = None,
-            data: bytes = None,
+            fetcher: Optional[Fetcher] = None,
+            meta: Optional[Dict[str, Any]] = None,
+            data: Optional[bytes] = None,
             flavors: Iterable[Flavor] = (),
             ) -> None:
         """
diff --git a/fimfarchive/tasks/build.py b/fimfarchive/tasks/build.py
index 5d09883..24392ae 100644
--- a/fimfarchive/tasks/build.py
+++ b/fimfarchive/tasks/build.py
@@ -52,8 +52,8 @@ class BuildTask:
             self,
             output: PathArg,
             upcoming: Iterable[Story],
-            previous: Fetcher = None,
-            extras: PathArg = None,
+            previous: Optional[Fetcher] = None,
+            extras: Optional[PathArg] = None,
             ) -> None:
         """
         Constructor.
diff --git a/fimfarchive/tasks/update.py b/fimfarchive/tasks/update.py
index 62de2b4..33ebc87 100644
--- a/fimfarchive/tasks/update.py
+++ b/fimfarchive/tasks/update.py
@@ -76,8 +76,8 @@ class UpdateTask(SignalSender):
             self,
             fimfarchive: Fetcher,
             fimfiction: Fetcher,
-            selector: Selector = None,
-            stamper: Stamper = None,
+            selector: Optional[Selector] = None,
+            stamper: Optional[Stamper] = None,
             workdir: str = DEFAULT_WORKDIR,
             retries: int = DEFAULT_RETRIES,
             skips: int = DEFAULT_SKIPS,
diff --git a/fimfarchive/utils.py b/fimfarchive/utils.py
index 4d0aa1f..34b80af 100644
--- a/fimfarchive/utils.py
+++ b/fimfarchive/utils.py
@@ -281,7 +281,11 @@ class ResourceLoader:
         self.package = package
         self.binary = binary
 
-    def __call__(self, name: str, binary: bool = None) -> Union[str, bytes]:
+    def __call__(
+            self,
+            name: str,
+            binary: Optional[bool] = None,
+            ) -> Union[str, bytes]:
         """
         Loads a package resource.
 
diff --git a/tests/test_utils.py b/tests/test_utils.py
index e571aa9..1937726 100644
--- a/tests/test_utils.py
+++ b/tests/test_utils.py
@@ -53,7 +53,7 @@ class TestEmpty:
         """
         Tests `Empty` class evaluates to `False`.
         """
-        assert not Empty
+        assert bool(Empty) is False
 
     def test_empty_class_is_empty(self):
         """