diff -ruN a/pdm/pep517/base.py b/pdm/pep517/base.py --- a/pdm/pep517/base.py 2022-08-06 17:29:41.927385300 +0200 +++ b/pdm/pep517/base.py 2022-08-23 17:45:23.391722696 +0200 @@ -7,7 +7,7 @@ from pathlib import Path from typing import Any, Iterator, Mapping, TypeVar, cast -from pdm.pep517._vendor import tomli +import tomli from pdm.pep517.exceptions import MetadataError, PDMWarning, ProjectError from pdm.pep517.metadata import Metadata from pdm.pep517.utils import is_python_package, safe_version, to_filename diff -ruN a/pdm/pep517/license.py b/pdm/pep517/license.py --- a/pdm/pep517/license.py 2022-08-06 17:29:41.927385300 +0200 +++ b/pdm/pep517/license.py 2022-08-23 17:45:23.391722696 +0200 @@ -1,6 +1,6 @@ import warnings -from pdm.pep517._vendor.license_expression import ( +from license_expression import ( LicenseSymbol, Licensing, get_spdx_licensing, diff -ruN a/pdm/pep517/metadata.py b/pdm/pep517/metadata.py --- a/pdm/pep517/metadata.py 2022-08-06 17:29:41.927385300 +0200 +++ b/pdm/pep517/metadata.py 2022-08-23 17:45:23.391722696 +0200 @@ -5,7 +5,7 @@ from pathlib import Path from typing import Any, Callable, Generic, Iterable, Mapping, TypeVar, cast -from pdm.pep517._vendor.packaging.requirements import Requirement +from packaging.requirements import Requirement from pdm.pep517.exceptions import MetadataError, PDMWarning, ProjectError from pdm.pep517.license import normalize_expression from pdm.pep517.utils import ( diff -ruN a/pdm/pep517/scm.py b/pdm/pep517/scm.py --- a/pdm/pep517/scm.py 2022-08-06 17:29:41.931385300 +0200 +++ b/pdm/pep517/scm.py 2022-08-23 17:45:23.391722696 +0200 @@ -14,8 +14,8 @@ from pathlib import Path from typing import Any, Iterable, NamedTuple -from pdm.pep517._vendor.packaging.version import LegacyVersion, Version -from pdm.pep517._vendor.packaging.version import parse as parse_version +from packaging.version import LegacyVersion, Version +from packaging.version import parse as parse_version DEFAULT_TAG_REGEX = re.compile( r"^(?:[\w-]+-)?(?P[vV]?\d+(?:\.\d+){0,2}[^\+]*)(?:\+.*)?$" diff -ruN a/pdm/pep517/sdist.py b/pdm/pep517/sdist.py --- a/pdm/pep517/sdist.py 2022-08-06 17:29:41.931385300 +0200 +++ b/pdm/pep517/sdist.py 2022-08-23 17:45:23.391722696 +0200 @@ -6,7 +6,8 @@ from copy import copy from typing import Any, Iterator -from pdm.pep517._vendor import tomli, tomli_w +import tomli +import tomli_w from pdm.pep517.base import Builder diff -ruN a/pdm/pep517/utils.py b/pdm/pep517/utils.py --- a/pdm/pep517/utils.py 2022-08-06 17:29:41.931385300 +0200 +++ b/pdm/pep517/utils.py 2022-08-23 17:45:23.391722696 +0200 @@ -11,10 +11,10 @@ from pathlib import Path from typing import Callable, Generator, Iterable -from pdm.pep517._vendor.packaging import tags -from pdm.pep517._vendor.packaging.markers import Marker -from pdm.pep517._vendor.packaging.requirements import InvalidRequirement, Requirement -from pdm.pep517._vendor.packaging.version import InvalidVersion, Version +from packaging import tags +from packaging.markers import Marker +from packaging.requirements import InvalidRequirement, Requirement +from packaging.version import InvalidVersion, Version from pdm.pep517.exceptions import MetadataError from pdm.pep517.macosx_platform import calculate_macosx_platform_tag diff -ruN a/pdm/pep517/validator.py b/pdm/pep517/validator.py --- a/pdm/pep517/validator.py 2022-08-06 17:29:41.931385300 +0200 +++ b/pdm/pep517/validator.py 2022-08-23 17:45:23.391722696 +0200 @@ -1,6 +1,6 @@ from typing import Mapping -from pdm.pep517._vendor import cerberus +import cerberus from pdm.pep517.exceptions import PEP621ValidationError README_RULE = [ diff -ruN a/pdm/pep517/wheel.py b/pdm/pep517/wheel.py --- a/pdm/pep517/wheel.py 2022-08-06 17:29:41.931385300 +0200 +++ b/pdm/pep517/wheel.py 2022-08-23 17:45:23.391722696 +0200 @@ -19,8 +19,8 @@ from typing import Any, BinaryIO, Generator, Mapping, NamedTuple, TextIO from pdm.pep517 import __version__ -from pdm.pep517._vendor.packaging import tags -from pdm.pep517._vendor.packaging.specifiers import SpecifierSet +from packaging import tags +from packaging.specifiers import SpecifierSet from pdm.pep517.base import Builder from pdm.pep517.exceptions import BuildError, PDMWarning from pdm.pep517.utils import get_abi_tag, get_platform, show_warning diff -ruN a/tests/test_metadata.py b/tests/test_metadata.py --- a/tests/test_metadata.py 2022-08-06 17:29:41.935385500 +0200 +++ b/tests/test_metadata.py 2022-08-23 17:45:23.391722696 +0200 @@ -5,7 +5,7 @@ import pytest -from pdm.pep517._vendor import tomli +import tomli from pdm.pep517.metadata import Metadata from tests import FIXTURES