diff --git a/dissect/cstruct/cstruct.py b/dissect/cstruct/cstruct.py
index 96f7ed5..2907734 100644
--- a/dissect/cstruct/cstruct.py
+++ b/dissect/cstruct/cstruct.py
@@ -30,8 +30,7 @@
 
 if TYPE_CHECKING:
     from collections.abc import Iterable
-
-    from typing_extensions import TypeAlias
+    from typing import TypeAlias
 
 
 T = TypeVar("T", bound=BaseType)
diff --git a/dissect/cstruct/expression.py b/dissect/cstruct/expression.py
index 0bb194f..88b9457 100644
--- a/dissect/cstruct/expression.py
+++ b/dissect/cstruct/expression.py
@@ -1,11 +1,13 @@
 from __future__ import annotations
 
 import string
-from typing import TYPE_CHECKING, Callable, ClassVar
+from typing import TYPE_CHECKING, ClassVar
 
 from dissect.cstruct.exceptions import ExpressionParserError, ExpressionTokenizerError
 
 if TYPE_CHECKING:
+    from collections.abc import Callable
+
     from dissect.cstruct import cstruct
 
 
diff --git a/dissect/cstruct/tools/stubgen.py b/dissect/cstruct/tools/stubgen.py
index 75694e3..02aaebb 100644
--- a/dissect/cstruct/tools/stubgen.py
+++ b/dissect/cstruct/tools/stubgen.py
@@ -39,10 +39,9 @@ def generate_file_stub(path: Path, base: Path) -> str:
 
     header = [
         "# Generated by cstruct-stubgen",
-        "from typing import BinaryIO, Literal, overload",
+        "from typing import BinaryIO, Literal, TypeAlias, overload",
         "",
         "import dissect.cstruct as __cs__",
-        "from typing_extensions import TypeAlias",
     ]
     body = []
 
diff --git a/dissect/cstruct/types/base.py b/dissect/cstruct/types/base.py
index 90c466c..d5ca7db 100644
--- a/dissect/cstruct/types/base.py
+++ b/dissect/cstruct/types/base.py
@@ -2,12 +2,14 @@
 
 import functools
 from io import BytesIO
-from typing import TYPE_CHECKING, Any, BinaryIO, Callable, ClassVar, TypeVar
+from typing import TYPE_CHECKING, Any, BinaryIO, ClassVar, TypeVar
 
 from dissect.cstruct.exceptions import ArraySizeError
 from dissect.cstruct.expression import Expression
 
 if TYPE_CHECKING:
+    from collections.abc import Callable
+
     from typing_extensions import Self
 
     from dissect.cstruct.cstruct import cstruct
@@ -60,10 +62,6 @@ def __bool__(cls) -> bool:
 
     def __len__(cls) -> int:
         """Return the byte size of the type."""
-        # Python 3.9 compat thing for bound type vars
-        if cls is BaseType:
-            return 0
-
         if cls.size is None:
             raise TypeError("Dynamic size")
 
diff --git a/dissect/cstruct/types/structure.py b/dissect/cstruct/types/structure.py
index 8d6d61b..f2e8e03 100644
--- a/dissect/cstruct/types/structure.py
+++ b/dissect/cstruct/types/structure.py
@@ -2,7 +2,7 @@
 
 import io
 from collections import ChainMap
-from collections.abc import MutableMapping
+from collections.abc import Callable, MutableMapping
 from contextlib import contextmanager
 from enum import Enum
 from functools import lru_cache
@@ -10,7 +10,7 @@
 from operator import attrgetter
 from textwrap import dedent
 from types import FunctionType
-from typing import TYPE_CHECKING, Any, BinaryIO, Callable
+from typing import TYPE_CHECKING, Any, BinaryIO
 
 from dissect.cstruct.bitbuffer import BitBuffer
 from dissect.cstruct.types.base import (
@@ -467,7 +467,7 @@ def __call__(cls, *args, **kwargs) -> Self:  # type: ignore
 
             # User (partial) initialization, rebuild the union
             # First user-provided field is the one used to rebuild the union
-            arg_fields = (field._name for _, field in zip(args, cls.__fields__))
+            arg_fields = (field._name for _, field in zip(args, cls.__fields__, strict=False))
             kwarg_fields = (name for name in kwargs if name in cls.lookup)
             if (first_field := next(chain(arg_fields, kwarg_fields), None)) is not None:
                 obj._rebuild(first_field)
diff --git a/pyproject.toml b/pyproject.toml
index d5d999a..9885573 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -1,13 +1,14 @@
 [build-system]
-requires = ["setuptools>=65.5.0", "setuptools_scm[toml]>=6.4.0"]
+requires = ["setuptools>=77.0.0", "setuptools_scm[toml]>=6.4.0"]
 build-backend = "setuptools.build_meta"
 
 [project]
 name = "dissect.cstruct"
 description = "A Dissect module implementing a parser for C-like structures: structure parsing in Python made easy"
 readme = "README.md"
-requires-python = "~=3.9"
-license.text = "Apache License 2.0"
+requires-python = ">=3.10"
+license =  "Apache-2.0"
+license-files = ["LICENSE", "COPYRIGHT"]
 authors = [
   {name = "Dissect Team", email = "dissect@fox-it.com"}
 ]
@@ -16,7 +17,6 @@ classifiers = [
   "Environment :: Console",
   "Intended Audience :: Developers",
   "Intended Audience :: Information Technology",
-  "License :: OSI Approved",
   "Operating System :: OS Independent",
   "Programming Language :: Python :: 3",
   "Topic :: Internet :: Log Analysis",
@@ -37,12 +37,33 @@ dev = [
   "typing_extensions"
 ]
 
+[dependency-groups]
+test = [
+    "pytest",
+]
+lint = [
+    "ruff==0.13.1",
+    "typing_extensions",
+    "vermin",
+]
+build = [
+    "build",
+]
+debug = [
+    "ipdb",
+]
+dev = [
+    {include-group = "test"},
+    {include-group = "lint"},
+    {include-group = "debug"},
+]
+
 [project.scripts]
 cstruct-stubgen = "dissect.cstruct.tools.stubgen:main"
 
 [tool.ruff]
 line-length = 120
-required-version = ">=0.12.0"
+required-version = ">=0.13.1"
 
 [tool.ruff.format]
 docstring-code-format = true
@@ -91,9 +112,6 @@ ignore = ["E203", "B904", "UP024", "ANN002", "ANN003", "ANN204", "ANN401", "SIM1
 known-first-party = ["dissect.cstruct"]
 known-third-party = ["dissect"]
 
-[tool.setuptools]
-license-files = ["LICENSE", "COPYRIGHT"]
-
 [tool.setuptools.packages.find]
 include = ["dissect.*"]
 
diff --git a/tests/test_basic.py b/tests/test_basic.py
index b4ef34d..bb0dd47 100644
--- a/tests/test_basic.py
+++ b/tests/test_basic.py
@@ -77,7 +77,7 @@ def test_load_init_kwargs_only() -> None:
     """
 
     # kwargs only check
-    with pytest.raises(TypeError, match="takes from .* positional arguments but .* were given"):
+    with pytest.raises(TypeError, match=r"takes from .* positional arguments but .* were given"):
         cs = cstruct(cdef, ">")
 
     cs = cstruct(cdef, endian=">")
diff --git a/tests/test_parser.py b/tests/test_parser.py
index f77da47..85a7906 100644
--- a/tests/test_parser.py
+++ b/tests/test_parser.py
@@ -282,7 +282,7 @@ def test_conditional_parsing_error(cs: cstruct) -> None:
     };
     #endif
     """
-    with pytest.raises(ParserError, match="line 8: unexpected token .+ENDIF"):
+    with pytest.raises(ParserError, match=r"line 8: unexpected token .+ENDIF"):
         cs.load(cdef)
 
     cdef = """
diff --git a/tests/test_tools_stubgen.py b/tests/test_tools_stubgen.py
index 5790d90..52e4f82 100644
--- a/tests/test_tools_stubgen.py
+++ b/tests/test_tools_stubgen.py
@@ -376,10 +376,9 @@ def test_generate_file_stub(tmp_path: Path, monkeypatch: pytest.MonkeyPatch, cap
 
     expected = """
         # Generated by cstruct-stubgen
-        from typing import BinaryIO, Literal, overload
+        from typing import BinaryIO, Literal, TypeAlias, overload
 
         import dissect.cstruct as __cs__
-        from typing_extensions import TypeAlias
 
         class _c_structure(__cs__.cstruct):
             class Test(__cs__.Structure):
diff --git a/tox.ini b/tox.ini
index 6dc6854..284a4ba 100644
--- a/tox.ini
+++ b/tox.ini
@@ -4,7 +4,7 @@ envlist = lint, py3, pypy3
 # requires if they are not available on the host system. This requires the
 # locally installed tox to have a minimum version 3.3.0. This means the names
 # of the configuration options are still according to the tox 3.x syntax.
-minversion = 4.4.3
+minversion = 4.27.0
 # This version of virtualenv will install setuptools version 68.2.2 and pip
 # 23.3.1. These versions fully support python projects defined only through a
 # pyproject.toml file (PEP-517/PEP-518/PEP-621). This pip version also support
@@ -14,9 +14,9 @@ requires = virtualenv>=20.24.6
 [testenv]
 extras = dev
 deps =
-    pytest
     pytest-cov
     coverage
+dependency_groups = test
 commands =
     pytest --basetemp="{envtmpdir}" {posargs:--color=yes --cov=dissect --cov-report=term-missing -v tests}
     coverage report
@@ -24,28 +24,24 @@ commands =
 
 [testenv:build]
 package = skip
-deps =
-    build
+dependency_groups = build
 commands =
     pyproject-build
 
 [testenv:fix]
 package = skip
-deps =
-    ruff==0.12.4
+dependency_groups = lint
 commands =
-    ruff format dissect tests
     ruff check --fix dissect tests
+    ruff format dissect tests
 
 [testenv:lint]
 package = skip
-deps =
-    ruff==0.12.4
-    vermin
+dependency_groups = lint
 commands =
-    ruff format --check dissect tests
     ruff check dissect tests
-    vermin -t=3.9- --no-tips --lint dissect tests
+    ruff format --check dissect tests
+    vermin -t=3.10- --no-tips --lint dissect tests
 
 [testenv:docs-build]
 allowlist_externals = make