diff --git a/docs/conf.py b/docs/conf.py
index 8861a6e8..58a37bce 100644
--- a/docs/conf.py
+++ b/docs/conf.py
@@ -17,18 +17,24 @@
         "obj",
         "compwa_policy.check_dev_files.dependabot.DependabotOption",
     ),
+    "IO": "typing.IO",
+    "Iterable": "typing.Iterable",
     "K": "typing.TypeVar",
+    "Mapping": "collections.abc.Mapping",
     "NotRequired": ("obj", "typing.NotRequired"),
-    "P": "typing.ParamSpec",
     "P.args": ("attr", "typing.ParamSpec.args"),
     "P.kwargs": ("attr", "typing.ParamSpec.kwargs"),
+    "P": "typing.ParamSpec",
     "Path": "pathlib.Path",
-    "PythonVersion": "typing.TypeVar",
+    "ProjectURLs": "list",
+    "PyprojectTOML": "dict",
+    "PythonVersion": "str",
+    "Sequence": "typing.Sequence",
     "T": "typing.TypeVar",
-    "TOMLDocument": "tomlkit.TOMLDocument",
     "Table": "tomlkit.items.Table",
-    "V": "typing.TypeVar",
+    "TOMLDocument": "tomlkit.TOMLDocument",
     "typing_extensions.NotRequired": ("obj", "typing.NotRequired"),
+    "V": "typing.TypeVar",
 }
 author = "Common Partial Wave Analysis"
 autodoc_member_order = "bysource"
@@ -102,6 +108,7 @@
 ]
 nitpick_ignore = [
     ("py:class", "CommentedMap"),
+    ("py:class", "ProjectURLs"),
 ]
 nitpick_ignore_regex = [
     ("py:class", r"^.*.[A-Z]$"),
diff --git a/src/compwa_policy/check_dev_files/black.py b/src/compwa_policy/check_dev_files/black.py
index d1e3e073..cd00dc0e 100644
--- a/src/compwa_policy/check_dev_files/black.py
+++ b/src/compwa_policy/check_dev_files/black.py
@@ -54,8 +54,8 @@ def _remove_outdated_settings(pyproject: ModifiablePyproject) -> None:
     removed_options = set()
     for option in forbidden_options:
         if option in settings:
+            settings.pop(option)
             removed_options.add(option)
-            settings.remove(option)
     if removed_options:
         msg = (
             f"Removed {', '.join(sorted(removed_options))} option from black"
diff --git a/src/compwa_policy/check_dev_files/pytest.py b/src/compwa_policy/check_dev_files/pytest.py
index 1be8dee0..96f30874 100644
--- a/src/compwa_policy/check_dev_files/pytest.py
+++ b/src/compwa_policy/check_dev_files/pytest.py
@@ -2,7 +2,7 @@
 
 from __future__ import annotations
 
-from typing import TYPE_CHECKING
+from typing import TYPE_CHECKING, Iterable
 
 import tomlkit
 from ini2toml.api import Translator
@@ -70,7 +70,7 @@ def _update_settings(pyproject: ModifiablePyproject) -> None:
         pyproject.append_to_changelog(msg)
 
 
-def __get_expected_addopts(existing: str | Array) -> Array:
+def __get_expected_addopts(existing: str | Iterable) -> Array:
     if isinstance(existing, str):
         options = {opt.strip() for opt in __split_options(existing)}
     else:
diff --git a/src/compwa_policy/check_dev_files/ruff.py b/src/compwa_policy/check_dev_files/ruff.py
index bd80515a..a37edc70 100644
--- a/src/compwa_policy/check_dev_files/ruff.py
+++ b/src/compwa_policy/check_dev_files/ruff.py
@@ -3,10 +3,10 @@
 from __future__ import annotations
 
 import os
-from typing import Iterable
+from collections import abc
+from typing import TYPE_CHECKING, Any, Iterable, Mapping
 
 from ruamel.yaml import YAML
-from tomlkit.items import Array, Table
 
 from compwa_policy.utilities import CONFIG_PATH, natural_sorting, remove_configs, vscode
 from compwa_policy.utilities.executor import Executor
@@ -25,6 +25,9 @@
 from compwa_policy.utilities.readme import add_badge, remove_badge
 from compwa_policy.utilities.toml import to_toml_array
 
+if TYPE_CHECKING:
+    from tomlkit.items import Array
+
 
 def main(has_notebooks: bool) -> None:
     with Executor() as do, ModifiablePyproject.load() as pyproject:
@@ -98,18 +101,17 @@ def __remove_nbqa_option(pyproject: ModifiablePyproject, option: str) -> None:
     nbqa_table = pyproject.get_table(table_key)
     if option not in nbqa_table:
         return
-    nbqa_table.remove(option)
+    nbqa_table.pop(option)
     msg = f"Removed {option!r} nbQA options from {CONFIG_PATH.pyproject}"
     pyproject.append_to_changelog(msg)
 
 
 def __remove_tool_table(pyproject: ModifiablePyproject, tool_table: str) -> None:
-    table_key = f"tool.{tool_table}"
-    if not pyproject.has_table(table_key):
-        return
-    pyproject._document["tool"].remove(tool_table)  # type: ignore[union-attr]
-    msg = f"Removed [tool.{tool_table}] section from {CONFIG_PATH.pyproject}"
-    pyproject.append_to_changelog(msg)
+    tools = pyproject._document.get("tool")
+    if isinstance(tools, dict) and tool_table in tools:
+        tools.pop(tool_table)
+        msg = f"Removed [tool.{tool_table}] section from {CONFIG_PATH.pyproject}"
+        pyproject.append_to_changelog(msg)
 
 
 def _remove_pydocstyle(pyproject: ModifiablePyproject) -> None:
@@ -153,11 +155,13 @@ def _move_ruff_lint_config(pyproject: ModifiablePyproject) -> None:
     }
     global_settings = pyproject.get_table("tool.ruff", create=True)
     lint_settings = {k: v for k, v in global_settings.items() if k in lint_option_keys}
-    lint_arrays = {k: v for k, v in lint_settings.items() if isinstance(v, Array)}
+    lint_arrays = {
+        k: v for k, v in lint_settings.items() if isinstance(v, abc.Sequence)
+    }
     if lint_arrays:
         lint_config = pyproject.get_table("tool.ruff.lint", create=True)
         lint_config.update(lint_arrays)
-    lint_tables = {k: v for k, v in lint_settings.items() if isinstance(v, Table)}
+    lint_tables = {k: v for k, v in lint_settings.items() if isinstance(v, abc.Mapping)}
     for table in lint_tables:
         lint_config = pyproject.get_table(f"tool.ruff.lint.{table}", create=True)
         lint_config.update(lint_tables[table])
@@ -322,7 +326,7 @@ def ___get_selected_ruff_rules(pyproject: Pyproject) -> Array:
     return to_toml_array(sorted(rules))
 
 
-def ___get_task_tags(ruff_settings: Table) -> Array:
+def ___get_task_tags(ruff_settings: Mapping[str, Any]) -> Array:
     existing: set[str] = set(ruff_settings.get("task-tags", set()))
     expected = {
         "cspell",
diff --git a/src/compwa_policy/utilities/pyproject/__init__.py b/src/compwa_policy/utilities/pyproject/__init__.py
index a49ad1ce..d8b12911 100644
--- a/src/compwa_policy/utilities/pyproject/__init__.py
+++ b/src/compwa_policy/utilities/pyproject/__init__.py
@@ -7,7 +7,17 @@
 from contextlib import AbstractContextManager
 from pathlib import Path
 from textwrap import indent
-from typing import IO, TYPE_CHECKING, Iterable, Sequence, TypeVar, overload
+from typing import (
+    IO,
+    TYPE_CHECKING,
+    Any,
+    Iterable,
+    Mapping,
+    MutableMapping,
+    Sequence,
+    TypeVar,
+    overload,
+)
 
 import tomlkit
 from attrs import field, frozen
@@ -22,6 +32,7 @@
     get_sub_table,
     get_supported_python_versions,
     has_sub_table,
+    load_pyproject_toml,
 )
 from compwa_policy.utilities.pyproject.setters import (
     add_dependency,
@@ -40,8 +51,7 @@
 if TYPE_CHECKING:
     from types import TracebackType
 
-    from tomlkit.items import Table
-    from tomlkit.toml_document import TOMLDocument
+    from compwa_policy.utilities.pyproject._struct import PyprojectTOML
 
 T = TypeVar("T", bound="Pyproject")
 
@@ -50,34 +60,24 @@
 class Pyproject:
     """Read-only representation of a :code:`pyproject.toml` file."""
 
-    _document: TOMLDocument
+    _document: PyprojectTOML
     _source: IO | Path | None = field(default=None)
 
     @final
     @classmethod
     def load(cls: type[T], source: IO | Path | str = CONFIG_PATH.pyproject) -> T:
         """Load a :code:`pyproject.toml` file from a file, I/O stream, or `str`."""
-        if isinstance(source, io.IOBase):
-            current_position = source.tell()
-            source.seek(0)
-            document = tomlkit.load(source)  # type:ignore[arg-type]
-            source.seek(current_position)
-            return cls(document, source)
-        if isinstance(source, Path):
-            with open(source) as stream:
-                document = tomlkit.load(stream)
-            return cls(document, source)
+        document = load_pyproject_toml(source)
         if isinstance(source, str):
-            return cls(tomlkit.loads(source))
-        msg = f"Source of type {type(source).__name__} is not supported"
-        raise TypeError(msg)
+            return cls(document)
+        return cls(document, source)
 
     @final
     def dumps(self) -> str:
         src = tomlkit.dumps(self._document, sort_keys=True)
         return f"{src.strip()}\n"
 
-    def get_table(self, dotted_header: str, create: bool = False) -> Table:
+    def get_table(self, dotted_header: str, create: bool = False) -> Mapping[str, Any]:
         if create:
             msg = "Cannot create sub-tables in a read-only pyproject.toml"
             raise TypeError(msg)
@@ -166,11 +166,13 @@ def dump(self, target: IO | Path | str | None = None) -> None:
             raise TypeError(msg)
 
     @override
-    def get_table(self, dotted_header: str, create: bool = False) -> Table:
+    def get_table(
+        self, dotted_header: str, create: bool = False
+    ) -> MutableMapping[str, Any]:
         self.__assert_is_in_context()
         if create:
             create_sub_table(self._document, dotted_header)
-        return super().get_table(dotted_header)
+        return super().get_table(dotted_header)  # type:ignore[return-value]
 
     def add_dependency(
         self, package: str, optional_key: str | Sequence[str] | None = None
@@ -200,7 +202,7 @@ def append_to_changelog(self, message: str) -> None:
         self._changelog.append(message)
 
 
-def complies_with_subset(settings: dict, minimal_settings: dict) -> bool:
+def complies_with_subset(settings: Mapping, minimal_settings: Mapping) -> bool:
     return all(settings.get(key) == value for key, value in minimal_settings.items())
 
 
diff --git a/src/compwa_policy/utilities/pyproject/_struct.py b/src/compwa_policy/utilities/pyproject/_struct.py
new file mode 100644
index 00000000..bf69e830
--- /dev/null
+++ b/src/compwa_policy/utilities/pyproject/_struct.py
@@ -0,0 +1,63 @@
+"""This module is hidden Sphinx can't handle `typing.TypedDict` with hyphens.
+
+See https://github.com/sphinx-doc/sphinx/issues/11039.
+"""
+
+import sys
+from typing import Dict, List
+
+if sys.version_info < (3, 8):
+    from typing_extensions import TypedDict
+else:
+    from typing import TypedDict
+if sys.version_info < (3, 11):
+    from typing_extensions import NotRequired
+else:
+    from typing import NotRequired
+
+PyprojectTOML = TypedDict(
+    "PyprojectTOML",
+    {
+        "build-system": NotRequired["BuildSystem"],
+        "project": "Project",
+        "tool": NotRequired[Dict[str, Dict[str, str]]],
+    },
+)
+"""Structure of a `pyproject.toml` file.
+
+See [pyproject.toml
+specification](https://packaging.python.org/en/latest/specifications/pyproject-toml).
+"""
+
+
+BuildSystem = TypedDict(
+    "BuildSystem",
+    {
+        "requires": List[str],
+        "build-backend": str,
+    },
+)
+
+
+Project = TypedDict(
+    "Project",
+    {
+        "name": str,
+        "version": NotRequired[str],
+        "dependencies": NotRequired[List[str]],
+        "optional-dependencies": NotRequired[Dict[str, List[str]]],
+        "urls": NotRequired["ProjectURLs"],
+    },
+)
+
+
+class ProjectURLs(TypedDict):
+    """Project  for PyPI."""
+
+    Changelog: NotRequired[str]
+    Documentation: NotRequired[str]
+    Homepage: NotRequired[str]
+    Issues: NotRequired[str]
+    Repository: NotRequired[str]
+    Source: NotRequired[str]
+    Tracker: NotRequired[str]
diff --git a/src/compwa_policy/utilities/pyproject/getters.py b/src/compwa_policy/utilities/pyproject/getters.py
index ad4463c1..20816c75 100644
--- a/src/compwa_policy/utilities/pyproject/getters.py
+++ b/src/compwa_policy/utilities/pyproject/getters.py
@@ -13,28 +13,29 @@
 from compwa_policy.errors import PrecommitError
 from compwa_policy.utilities import CONFIG_PATH
 
+if TYPE_CHECKING:
+    from collections.abc import Mapping
+
+    from compwa_policy.utilities.pyproject._struct import ProjectURLs, PyprojectTOML
+
 if sys.version_info < (3, 8):
     from typing_extensions import Literal
 else:
     from typing import Literal
-if TYPE_CHECKING:
-    from tomlkit.container import Container
-    from tomlkit.items import Table
-    from tomlkit.toml_document import TOMLDocument
 
 
 PythonVersion = Literal["3.6", "3.7", "3.8", "3.9", "3.10", "3.11", "3.12"]
 
 
 @overload
-def get_package_name(doc: TOMLDocument) -> str | None: ...
+def get_package_name(doc: PyprojectTOML) -> str | None: ...
 @overload
 def get_package_name(
-    doc: TOMLDocument, raise_on_missing: Literal[False]
+    doc: PyprojectTOML, raise_on_missing: Literal[False]
 ) -> str | None: ...
 @overload
-def get_package_name(doc: TOMLDocument, raise_on_missing: Literal[True]) -> str: ...
-def get_package_name(doc: TOMLDocument, raise_on_missing: bool = False):  # type: ignore[no-untyped-def]
+def get_package_name(doc: PyprojectTOML, raise_on_missing: Literal[True]) -> str: ...
+def get_package_name(doc: PyprojectTOML, raise_on_missing: bool = False):  # type: ignore[no-untyped-def]
     if not has_sub_table(doc, "project"):
         if raise_on_missing:
             msg = "Please provide a name for the package under the [project] table in pyproject.toml"
@@ -47,7 +48,7 @@ def get_package_name(doc: TOMLDocument, raise_on_missing: bool = False):  # type
     return package_name
 
 
-def get_project_urls(pyproject: TOMLDocument) -> Table:
+def get_project_urls(pyproject: PyprojectTOML) -> ProjectURLs:
     project_table = get_sub_table(pyproject, "project")
     urls = project_table.get("urls")
     if urls is None:
@@ -64,7 +65,7 @@ def get_project_urls(pyproject: TOMLDocument) -> Table:
     return urls
 
 
-def get_source_url(pyproject: TOMLDocument) -> str:
+def get_source_url(pyproject: PyprojectTOML) -> str:
     urls = get_project_urls(pyproject)
     source_url = urls.get("Source")
     if source_url is None:
@@ -73,7 +74,7 @@ def get_source_url(pyproject: TOMLDocument) -> str:
     return source_url
 
 
-def get_supported_python_versions(pyproject: TOMLDocument) -> list[PythonVersion]:
+def get_supported_python_versions(pyproject: PyprojectTOML) -> list[PythonVersion]:
     """Extract sorted list of supported Python versions from package classifiers.
 
     >>> import tomlkit
@@ -120,9 +121,9 @@ def _extract_python_versions(classifiers: list[str]) -> list[PythonVersion]:
     return [s.replace(prefix, "") for s in version_classifiers]  # type: ignore[misc]
 
 
-def get_sub_table(config: Container, dotted_header: str) -> Table:
+def get_sub_table(config: Mapping[str, Any], dotted_header: str) -> Mapping[str, Any]:
     """Get a TOML sub-table through a dotted header key."""
-    current_table: Any = config
+    current_table = config
     for header in dotted_header.split("."):
         if header not in current_table:
             msg = f"TOML data does not contain {dotted_header!r}"
@@ -131,7 +132,7 @@ def get_sub_table(config: Container, dotted_header: str) -> Table:
     return current_table
 
 
-def has_sub_table(config: Container, dotted_header: str) -> bool:
+def has_sub_table(config: Mapping[str, Any], dotted_header: str) -> bool:
     current_table: Any = config
     for header in dotted_header.split("."):
         if header in current_table:
@@ -143,7 +144,7 @@ def has_sub_table(config: Container, dotted_header: str) -> bool:
 
 def load_pyproject_toml(
     source: IO | Path | str = CONFIG_PATH.pyproject,
-) -> TOMLDocument:
+) -> PyprojectTOML:
     """Load a :code:`pyproject.toml` file from a file, I/O stream, or `str`."""
     if isinstance(source, io.IOBase):
         current_position = source.tell()
@@ -153,8 +154,8 @@ def load_pyproject_toml(
         return document
     if isinstance(source, Path):
         with open(source) as stream:
-            return tomlkit.load(stream)
+            return tomlkit.load(stream)  # type:ignore[return-value]
     if isinstance(source, str):
-        return tomlkit.loads(source)
+        return tomlkit.loads(source)  # type:ignore[return-value]
     msg = f"Source of type {type(source).__name__} is not supported"
     raise TypeError(msg)
diff --git a/src/compwa_policy/utilities/pyproject/setters.py b/src/compwa_policy/utilities/pyproject/setters.py
index e304b628..242ed8b9 100644
--- a/src/compwa_policy/utilities/pyproject/setters.py
+++ b/src/compwa_policy/utilities/pyproject/setters.py
@@ -3,26 +3,28 @@
 from __future__ import annotations
 
 from collections import abc
-from typing import TYPE_CHECKING, Any, Iterable, Sequence
+from typing import TYPE_CHECKING, Any, Iterable, Mapping, MutableMapping, Sequence, cast
 
 import tomlkit
-from tomlkit import TOMLDocument
 
-from compwa_policy.utilities.pyproject.getters import get_package_name, get_sub_table
+from compwa_policy.utilities.pyproject.getters import get_package_name
+from compwa_policy.utilities.pyproject.getters import (
+    get_sub_table as get_immutable_sub_table,
+)
 from compwa_policy.utilities.toml import to_toml_array
 
 if TYPE_CHECKING:
-    from tomlkit.container import Container
     from tomlkit.items import Table
 
+    from compwa_policy.utilities.pyproject._struct import PyprojectTOML
+
 
 def add_dependency(
-    pyproject: TOMLDocument,
+    pyproject: PyprojectTOML,
     package: str,
     optional_key: str | Sequence[str] | None = None,
 ) -> bool:
     if optional_key is None:
-        create_sub_table(pyproject, "project")
         project = get_sub_table(pyproject, "project")
         existing_dependencies: set[str] = set(project.get("dependencies", []))
         if package in existing_dependencies:
@@ -32,7 +34,6 @@ def add_dependency(
         return True
     if isinstance(optional_key, str):
         table_key = "project.optional-dependencies"
-        create_sub_table(pyproject, table_key)
         optional_dependencies = get_sub_table(pyproject, table_key)
         existing_dependencies = set(optional_dependencies.get(optional_key, []))
         if package in existing_dependencies:
@@ -63,7 +64,7 @@ def _sort_taplo(items: Iterable[str]) -> list[str]:
     return sorted(items, key=lambda s: ('"' in s, s))
 
 
-def create_sub_table(config: Container, dotted_header: str) -> Table:
+def create_sub_table(config: Mapping[str, Any], dotted_header: str) -> Table:
     """Create a TOML sub-table through a dotted header key."""
     current_table: Any = config
     for header in dotted_header.split("."):
@@ -73,8 +74,16 @@ def create_sub_table(config: Container, dotted_header: str) -> Table:
     return current_table
 
 
+def get_sub_table(
+    config: Mapping[str, Any], dotted_header: str
+) -> MutableMapping[str, Any]:
+    create_sub_table(config, dotted_header)
+    table = get_immutable_sub_table(config, dotted_header)
+    return cast(MutableMapping[str, Any], table)
+
+
 def remove_dependency(
-    pyproject: TOMLDocument,
+    pyproject: PyprojectTOML,
     package: str,
     ignored_sections: Iterable[str] | None = None,
 ) -> bool:
diff --git a/tests/utilities/pyproject/test_getters.py b/tests/utilities/pyproject/test_getters.py
index dd0726da..cb4014ba 100644
--- a/tests/utilities/pyproject/test_getters.py
+++ b/tests/utilities/pyproject/test_getters.py
@@ -1,5 +1,4 @@
 import pytest
-import tomlkit
 
 from compwa_policy.errors import PrecommitError
 from compwa_policy.utilities.pyproject.getters import (
@@ -9,11 +8,12 @@
     get_sub_table,
     get_supported_python_versions,
     has_sub_table,
+    load_pyproject_toml,
 )
 
 
 def test_get_package_name():
-    src = tomlkit.loads("""
+    src = load_pyproject_toml("""
         [project]
         name = "my-package"
     """)
@@ -22,7 +22,7 @@ def test_get_package_name():
 
 
 def test_get_package_name_missing():
-    src = tomlkit.loads("""
+    src = load_pyproject_toml("""
         [server]
         ip = "192.168.1.1"
         port = 8000
@@ -43,7 +43,7 @@ def test_get_package_name_missing():
 
 
 def test_get_project_urls():
-    pyproject = tomlkit.loads("""
+    pyproject = load_pyproject_toml("""
         [project]
         name = "my-package"
 
@@ -61,7 +61,7 @@ def test_get_project_urls():
 
 
 def test_get_project_urls_missing():
-    pyproject = tomlkit.loads("""
+    pyproject = load_pyproject_toml("""
         [project]
         name = "my-package"
     """)
@@ -73,7 +73,7 @@ def test_get_project_urls_missing():
 
 
 def test_get_source_url_missing():
-    pyproject = tomlkit.loads("""
+    pyproject = load_pyproject_toml("""
         [project.urls]
         Documentation = "https://ampform.rtfd.io"
     """)
@@ -85,7 +85,7 @@ def test_get_source_url_missing():
 
 
 def test_get_supported_python_versions():
-    pyproject = tomlkit.loads("""
+    pyproject = load_pyproject_toml("""
         [project]
         name = "my-package"
         classifiers = [
@@ -100,7 +100,7 @@ def test_get_supported_python_versions():
 
 
 def test_get_sub_table():
-    document = tomlkit.loads("""
+    document = load_pyproject_toml("""
         [project]
         name = "my-package"
 
@@ -124,7 +124,7 @@ def test_get_sub_table():
 
 
 def test_has_sub_table():
-    document = tomlkit.loads("""
+    document = load_pyproject_toml("""
         [project]
         name = "my-package"
 
diff --git a/tests/utilities/pyproject/test_setters.py b/tests/utilities/pyproject/test_setters.py
index 0623bdbd..4343882b 100644
--- a/tests/utilities/pyproject/test_setters.py
+++ b/tests/utilities/pyproject/test_setters.py
@@ -2,8 +2,9 @@
 
 import pytest
 import tomlkit
-from tomlkit import TOMLDocument
 
+from compwa_policy.utilities.pyproject._struct import PyprojectTOML
+from compwa_policy.utilities.pyproject.getters import load_pyproject_toml
 from compwa_policy.utilities.pyproject.setters import (
     add_dependency,
     create_sub_table,
@@ -12,7 +13,7 @@
 
 
 def test_add_dependency():
-    pyproject = tomlkit.loads("""
+    pyproject = load_pyproject_toml("""
         [project]
         name = "my-package"
     """)
@@ -29,7 +30,7 @@ def test_add_dependency():
 
 
 def test_add_dependency_existing():
-    pyproject = tomlkit.loads("""
+    pyproject = load_pyproject_toml("""
         [project]
         dependencies = ["attrs"]
 
@@ -49,7 +50,7 @@ def test_add_dependency_nested():
         name = "my-package"
     """)
 
-    pyproject = tomlkit.loads(src)
+    pyproject = load_pyproject_toml(src)
     add_dependency(pyproject, "ruff", optional_key=["lint", "sty", "dev"])
 
     new_content = tomlkit.dumps(pyproject)
@@ -70,7 +71,7 @@ def test_add_dependency_optional():
         [project]
         name = "my-package"
     """)
-    pyproject = tomlkit.loads(src)
+    pyproject = load_pyproject_toml(src)
     add_dependency(pyproject, "ruff", optional_key="lint")
 
     new_content = tomlkit.dumps(pyproject)
@@ -85,7 +86,7 @@ def test_add_dependency_optional():
 
 
 @pytest.fixture(scope="function")
-def pyproject_example() -> TOMLDocument:
+def pyproject_example() -> PyprojectTOML:
     src = dedent("""
         [project]
         name = "my-package"
@@ -98,10 +99,10 @@ def pyproject_example() -> TOMLDocument:
         ]
         sty = ["ruff"]
     """)
-    return tomlkit.loads(src)
+    return load_pyproject_toml(src)
 
 
-def test_remove_dependency(pyproject_example: TOMLDocument):
+def test_remove_dependency(pyproject_example: PyprojectTOML):
     remove_dependency(pyproject_example, "attrs")
     expected = dedent("""
         [project]
@@ -119,7 +120,7 @@ def test_remove_dependency(pyproject_example: TOMLDocument):
     assert new_content == expected
 
 
-def test_remove_dependency_nested(pyproject_example: TOMLDocument):
+def test_remove_dependency_nested(pyproject_example: PyprojectTOML):
     remove_dependency(pyproject_example, "ruff", ignored_sections=["sty"])
     new_content = tomlkit.dumps(pyproject_example)
     expected = dedent("""
@@ -138,7 +139,7 @@ def test_remove_dependency_nested(pyproject_example: TOMLDocument):
 
 @pytest.mark.parametrize("table_key", ["project", "project.optional-dependencies"])
 def test_create_sub_table(table_key: str):
-    pyproject = tomlkit.loads("")
+    pyproject = load_pyproject_toml("")
     dependencies = create_sub_table(pyproject, table_key)
 
     new_content = tomlkit.dumps(pyproject)
diff --git a/tests/utilities/test_pyproject.py b/tests/utilities/test_pyproject.py
index 3e851b1e..86656e74 100644
--- a/tests/utilities/test_pyproject.py
+++ b/tests/utilities/test_pyproject.py
@@ -4,7 +4,6 @@
 from textwrap import dedent
 
 import pytest
-from tomlkit.items import Table
 
 from compwa_policy.utilities.pyproject import ModifiablePyproject, Pyproject
 from compwa_policy.utilities.toml import to_toml_array
@@ -39,8 +38,12 @@ def test_load_from_str(self):
             name = "my-package"
             requires-python = ">=3.7"
         """)
-        assert isinstance(pyproject._document["build-system"], Table)
-        assert pyproject._document["project"]["dependencies"] == [  # type: ignore[index]
+        assert set(pyproject._document) == {
+            "build-system",
+            "project",
+        }
+        project = pyproject.get_table("project")
+        assert project.get("dependencies") == [
             "attrs",
             "sympy >=1.10",
         ]