diff --git a/.pre-commit-config.yaml b/.pre-commit-config.yaml
index f858fc1..233578a 100644
--- a/.pre-commit-config.yaml
+++ b/.pre-commit-config.yaml
@@ -21,7 +21,7 @@ repos:
   hooks:
     - id: vermin-all
       # specify your target version here, OR in a Vermin config file as usual:
-      args: ['-t=3.8-', '--no-tips', '--violations', '--exclude', 'enum.StrEnum', '.']
+      args: ['-t=3.8-', '--no-tips', '--violations', '--exclude', 'enum.StrEnum', '--exclude', 'types.UnionType', '.']
 - repo: https://github.com/commitizen-tools/commitizen
   rev: v3.20.0
   hooks:
diff --git a/TODO.md b/TODO.md
index b6e8048..c2339f5 100644
--- a/TODO.md
+++ b/TODO.md
@@ -1,16 +1,30 @@
 # TODO
 
-## v0.4.0
+## v0.3.1
 
+- `ConfigDataclass`: rename `configure` to `as_config`?
 - Github Actions for automated testing
-  - Coverage badge
+  - Special branch prefix to not run pipeline
+  - Badges (shields.io)
+    - Version
+    - Coverage
+    - CI status
+    - Read the Docs
+    - PyPI version
   - Auto-publish when new tag is pushed (see: https://pypi.org/manage/project/fancy-dataclass/settings/publishing/)
       - Require tag to match version?
-- `DictConfig` subclass of `Config` (unstructured configs loaded from JSON/TOML)
+      - Do "hatch version" and check if it's a prefix of "git describe --tags" or matches "git describe --tags --abbrev=0"
+  - PyPI Links
+    - Changelog
 - Release
   - CHANGELOG update
+    - pre-push hook to ensure it contains an entry for the latest tag
   - Tag new version
 
+## v0.4.0
+
+- `DictConfig` subclass of `Config` (unstructured configs loaded from JSON/TOML)
+
 ## v0.4.1
 
 - documentation
@@ -51,6 +65,7 @@
   - PEP 712 (`converter` argument for dataclass fields)
   - Allow `Annotated` as an alternative to `field.metadata`
     - Esp. with `Doc`: this could auto-populate JSON schema, argparse description
+- Tiered configs?
 - Improve `mkdocs` documentation
   - Auto-generate per-field descriptions via PEP 727?
   - Auto-generate dataclass field docs?
diff --git a/fancy_dataclass/dict.py b/fancy_dataclass/dict.py
index f00f5d6..f96d9e4 100644
--- a/fancy_dataclass/dict.py
+++ b/fancy_dataclass/dict.py
@@ -8,7 +8,7 @@
 from typing_extensions import Self, _AnnotatedAlias
 
 from fancy_dataclass.mixin import DataclassMixin, DataclassMixinSettings, FieldSettings
-from fancy_dataclass.utils import TypeConversionError, _flatten_dataclass, check_dataclass, fully_qualified_class_name, issubclass_safe, obj_class_name, safe_dict_insert, type_is_optional
+from fancy_dataclass.utils import TypeConversionError, _flatten_dataclass, check_dataclass, fully_qualified_class_name, issubclass_safe, obj_class_name, safe_dict_insert
 
 
 if TYPE_CHECKING:
@@ -250,10 +250,6 @@ def err() -> TypeConversionError:
                     return tuple(convert_val(subtype, elt) for elt in val)
                 return tuple(convert_val(subtype, elt) for (subtype, elt) in zip(args, val))
             elif origin_type == Union:
-                if type_is_optional(tp):
-                    assert len(args) == 2
-                    assert args[1] is type(None)
-                    args = args[::-1]  # check None first
                 for subtype in args:
                     try:
                         # NB: will resolve to the first valid type in the Union
diff --git a/fancy_dataclass/utils.py b/fancy_dataclass/utils.py
index cdba414..9ae4897 100644
--- a/fancy_dataclass/utils.py
+++ b/fancy_dataclass/utils.py
@@ -9,6 +9,7 @@
 import importlib
 from pathlib import Path
 import re
+import types
 from typing import TYPE_CHECKING, Any, BinaryIO, Callable, Dict, ForwardRef, Generic, Iterable, Iterator, List, Optional, Sequence, Set, TextIO, Tuple, Type, TypeVar, Union, get_args, get_origin, get_type_hints
 
 from typing_extensions import TypeGuard
@@ -55,7 +56,10 @@ def type_is_optional(tp: type) -> bool:
         True if the type is Optional"""
     origin_type = get_origin(tp)
     args = get_args(tp)
-    return (origin_type == Union) and (len(args) == 2) and (type(None) in args)
+    union_types: List[Any] = [Union]
+    if hasattr(types, 'UnionType'):  # Python >= 3.10
+        union_types.append(types.UnionType)
+    return (origin_type in union_types) and (type(None) in args)
 
 def safe_dict_insert(d: Dict[Any, Any], key: str, val: Any) -> None:
     """Inserts a (key, value) pair into a dict, if the key is not already present.
diff --git a/pyproject.toml b/pyproject.toml
index 0e93f60..ca11a43 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -5,7 +5,7 @@ build-backend = "hatchling.build"
 [project]
 name = "fancy-dataclass"
 dynamic = ["version"]
-description = "Spiff up your dataclasses with additional features."
+description = "Spiff up your dataclasses with extra features."
 readme = "docs/README.md"
 requires-python = ">=3.8"
 license = "MIT"
@@ -62,7 +62,7 @@ dependencies = [
 
 [tool.hatch.envs.lint.scripts]
 run-ruff = "ruff check"
-run-vermin = "vermin {args:-t=3.8- --eval-annotations --no-tips --violations --exclude 'tests.test_serializable.StrEnum' fancy_dataclass}"
+run-vermin = "vermin {args:-t=3.8- --eval-annotations --no-tips --violations --exclude enum.StrEnum --exclude types.UnionType .}"
 run-mypy = "mypy --install-types --non-interactive {args:fancy_dataclass tests}"
 run-loc-summary = "./summarize.sh"
 all = ["run-ruff", "run-vermin", "run-mypy", "run-loc-summary"]
diff --git a/tests/test_utils.py b/tests/test_utils.py
index 60d1b87..5b633c7 100644
--- a/tests/test_utils.py
+++ b/tests/test_utils.py
@@ -1,4 +1,5 @@
 from dataclasses import dataclass, is_dataclass
+import sys
 from typing import Any, ClassVar, Dict, List, Optional, Sequence, Union
 
 import pytest
@@ -9,16 +10,26 @@
 
 @pytest.mark.parametrize(['tp', 'is_optional'], [
     (int, False),
+    (type(None), False),
     (Optional[int], True),
     (Optional[Optional[int]], True),
-    (Union[int, Optional[float]], False),
-    (Union[Optional[float], int], False),
+    (Union[int, Optional[float]], True),
+    (Union[Optional[float], int], True),
     (Optional[type(None)], False),  # Optional[NoneType] -> NoneType
     (List[Optional[int]], False),
 ])
 def test_type_is_optional(tp, is_optional):
     assert type_is_optional(tp) == is_optional
 
+@pytest.mark.skipif(sys.version_info[:2] < (3, 10), reason='Py3.10 union type')
+def test_type_is_optional_py39():
+    assert type_is_optional(int | None)
+    assert type_is_optional(None | int)
+    assert type_is_optional(None | int | str)
+    assert type_is_optional(int | str | None)
+    assert type_is_optional(Optional[int | str])
+    assert type_is_optional(Optional[int] | str)
+
 @pytest.mark.parametrize(['obj', 'tp', 'output'], [
     (1, int, True),
     ('a', int, False),