diff --git a/CHANGES b/CHANGES
index 8909f66e24..d9c7ec5bb2 100644
--- a/CHANGES
+++ b/CHANGES
@@ -19,6 +19,16 @@ $ pipx install --suffix=@next 'tmuxp' --pip-args '\--pre' --force
 
 <!-- Maintainers, insert changes / features for the next release here -->
 
+### Development
+
+- Aggressive automated lint fixes via `ruff` (#953)
+
+  via ruff v0.8.4, all automated lint fixes, including unsafe and previews were applied for Python 3.9:
+
+  ```sh
+  ruff check --select ALL . --fix --unsafe-fixes --preview --show-fixes; ruff format .
+  ```
+
 ## tmuxp 1.49.0 (2024-11-26)
 
 _Maintenance only, no bug fixes or new features_
diff --git a/conftest.py b/conftest.py
index 16899a7a2c..54d0b18bb0 100644
--- a/conftest.py
+++ b/conftest.py
@@ -84,7 +84,7 @@ def monkeypatch_plugin_test_packages(monkeypatch: pytest.MonkeyPatch) -> None:
 
 
 @pytest.fixture
-def session_params(session_params: t.Dict[str, t.Any]) -> t.Dict[str, t.Any]:
+def session_params(session_params: dict[str, t.Any]) -> dict[str, t.Any]:
     """Terminal-friendly tmuxp session_params for dimensions."""
     session_params.update({"x": 800, "y": 600})
     return session_params
@@ -99,7 +99,7 @@ def socket_name(request: pytest.FixtureRequest) -> str:
 @pytest.fixture(autouse=True)
 def add_doctest_fixtures(
     request: pytest.FixtureRequest,
-    doctest_namespace: t.Dict[str, t.Any],
+    doctest_namespace: dict[str, t.Any],
     tmp_path: pathlib.Path,
 ) -> None:
     """Harness pytest fixtures to doctests namespace."""
diff --git a/docs/_ext/aafig.py b/docs/_ext/aafig.py
index 88b12c78d1..987cc39825 100644
--- a/docs/_ext/aafig.py
+++ b/docs/_ext/aafig.py
@@ -40,9 +40,9 @@
 
 
 def merge_dict(
-    dst: t.Dict[str, t.Optional[str]],
-    src: t.Dict[str, t.Optional[str]],
-) -> t.Dict[str, t.Optional[str]]:
+    dst: dict[str, t.Optional[str]],
+    src: dict[str, t.Optional[str]],
+) -> dict[str, t.Optional[str]]:
     for k, v in src.items():
         if k not in dst:
             dst[k] = v
@@ -51,15 +51,15 @@ def merge_dict(
 
 def get_basename(
     text: str,
-    options: t.Dict[str, str],
+    options: dict[str, str],
     prefix: t.Optional[str] = "aafig",
 ) -> str:
     options = options.copy()
     if "format" in options:
         del options["format"]
     hashkey = text + str(options)
-    _id = sha(hashkey.encode("utf-8")).hexdigest()
-    return f"{prefix}-{_id}"
+    id_ = sha(hashkey.encode("utf-8")).hexdigest()
+    return f"{prefix}-{id_}"
 
 
 class AafigError(SphinxError):
@@ -83,7 +83,7 @@ class AafigDirective(images.Image):  # type:ignore
     option_spec = images.Image.option_spec.copy()
     option_spec.update(own_option_spec)
 
-    def run(self) -> t.List[nodes.Node]:
+    def run(self) -> list[nodes.Node]:
         aafig_options = {}
         own_options_keys = [self.own_option_spec.keys(), "scale"]
         for k, v in self.options.items():
@@ -120,13 +120,13 @@ def render_aafig_images(app: "Sphinx", doctree: nodes.Node) -> None:
             continue
         options = img.aafig["options"]
         text = img.aafig["text"]
-        _format = app.builder.format
+        format_ = app.builder.format
         merge_dict(options, app.builder.config.aafig_default_options)
-        if _format in format_map:
-            options["format"] = format_map[_format]
+        if format_ in format_map:
+            options["format"] = format_map[format_]
         else:
             logger.warning(
-                f'unsupported builder format "{_format}", please '
+                f'unsupported builder format "{format_}", please '
                 "add a custom entry in aafig_format config "
                 "option for this builder",
             )
@@ -159,8 +159,8 @@ def __init__(self, *args: object, **kwargs: object) -> None:
 def render_aafigure(
     app: "Sphinx",
     text: str,
-    options: t.Dict[str, str],
-) -> t.Tuple[str, str, t.Optional[str], t.Optional[str]]:
+    options: dict[str, str],
+) -> tuple[str, str, t.Optional[str], t.Optional[str]]:
     """Render an ASCII art figure into the requested format output file."""
     if aafigure is None:
         raise AafigureNotInstalled
diff --git a/docs/conf.py b/docs/conf.py
index 6f232aa41c..980b848890 100644
--- a/docs/conf.py
+++ b/docs/conf.py
@@ -22,7 +22,7 @@
 sys.path.insert(0, str(cwd / "_ext"))
 
 # package data
-about: t.Dict[str, str] = {}
+about: dict[str, str] = {}
 with (src_root / "tmuxp" / "__about__.py").open() as fp:
     exec(fp.read(), about)
 
@@ -73,8 +73,8 @@
 html_static_path = ["_static"]
 html_favicon = "_static/favicon.ico"
 html_theme = "furo"
-html_theme_path: t.List[str] = []
-html_theme_options: t.Dict[str, t.Union[str, t.List[t.Dict[str, str]]]] = {
+html_theme_path: list[str] = []
+html_theme_options: dict[str, t.Union[str, list[dict[str, str]]]] = {
     "light_logo": "img/tmuxp.svg",
     "dark_logo": "img/tmuxp.svg",
     "footer_icons": [
@@ -143,7 +143,7 @@
 }
 
 
-def linkcode_resolve(domain: str, info: t.Dict[str, str]) -> t.Union[None, str]:
+def linkcode_resolve(domain: str, info: dict[str, str]) -> t.Union[None, str]:
     """
     Determine the URL corresponding to Python object.
 
diff --git a/pyproject.toml b/pyproject.toml
index 953a65175e..d7caaef55f 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -153,6 +153,7 @@ exclude_lines = [
 
 [tool.mypy]
 strict = true
+python_version = "3.9"
 files = [
   "src/",
   "tests/",
@@ -171,7 +172,7 @@ module = [
 ignore_missing_imports = true
 
 [tool.ruff]
-target-version = "py38"
+target-version = "py39"
 
 [tool.ruff.lint]
 select = [
diff --git a/src/tmuxp/_internal/config_reader.py b/src/tmuxp/_internal/config_reader.py
index 4ca6aa82a3..6cd862edb9 100644
--- a/src/tmuxp/_internal/config_reader.py
+++ b/src/tmuxp/_internal/config_reader.py
@@ -11,7 +11,7 @@
 
     FormatLiteral = t.Literal["json", "yaml"]
 
-    RawConfigData: TypeAlias = t.Dict[t.Any, t.Any]
+    RawConfigData: TypeAlias = dict[t.Any, t.Any]
 
 
 class ConfigReader:
@@ -28,7 +28,7 @@ def __init__(self, content: "RawConfigData") -> None:
         self.content = content
 
     @staticmethod
-    def _load(fmt: "FormatLiteral", content: str) -> t.Dict[str, t.Any]:
+    def _load(fmt: "FormatLiteral", content: str) -> dict[str, t.Any]:
         """Load raw config data and directly return it.
 
         >>> ConfigReader._load("json", '{ "session_name": "my session" }')
@@ -39,14 +39,14 @@ def _load(fmt: "FormatLiteral", content: str) -> t.Dict[str, t.Any]:
         """
         if fmt == "yaml":
             return t.cast(
-                t.Dict[str, t.Any],
+                "dict[str, t.Any]",
                 yaml.load(
                     content,
                     Loader=yaml.SafeLoader,
                 ),
             )
         if fmt == "json":
-            return t.cast(t.Dict[str, t.Any], json.loads(content))
+            return t.cast("dict[str, t.Any]", json.loads(content))
         msg = f"{fmt} not supported in configuration"
         raise NotImplementedError(msg)
 
@@ -74,7 +74,7 @@ def load(cls, fmt: "FormatLiteral", content: str) -> "ConfigReader":
         )
 
     @classmethod
-    def _from_file(cls, path: pathlib.Path) -> t.Dict[str, t.Any]:
+    def _from_file(cls, path: pathlib.Path) -> dict[str, t.Any]:
         r"""Load data from file path directly to dictionary.
 
         **YAML file**
diff --git a/src/tmuxp/_internal/types.py b/src/tmuxp/_internal/types.py
index 42b55a82f7..aa2d9444db 100644
--- a/src/tmuxp/_internal/types.py
+++ b/src/tmuxp/_internal/types.py
@@ -10,8 +10,6 @@
 ...
 """
 
-import typing as t
-
 from typing_extensions import NotRequired, TypedDict
 
 
@@ -19,10 +17,10 @@ class PluginConfigSchema(TypedDict):
     plugin_name: NotRequired[str]
     tmux_min_version: NotRequired[str]
     tmux_max_version: NotRequired[str]
-    tmux_version_incompatible: NotRequired[t.List[str]]
+    tmux_version_incompatible: NotRequired[list[str]]
     libtmux_min_version: NotRequired[str]
     libtmux_max_version: NotRequired[str]
-    libtmux_version_incompatible: NotRequired[t.List[str]]
+    libtmux_version_incompatible: NotRequired[list[str]]
     tmuxp_min_version: NotRequired[str]
     tmuxp_max_version: NotRequired[str]
-    tmuxp_version_incompatible: NotRequired[t.List[str]]
+    tmuxp_version_incompatible: NotRequired[list[str]]
diff --git a/src/tmuxp/cli/__init__.py b/src/tmuxp/cli/__init__.py
index e1ee765a77..f285cb7d9c 100644
--- a/src/tmuxp/cli/__init__.py
+++ b/src/tmuxp/cli/__init__.py
@@ -118,7 +118,7 @@ class CLINamespace(argparse.Namespace):
 ns = CLINamespace()
 
 
-def cli(_args: t.Optional[t.List[str]] = None) -> None:
+def cli(_args: t.Optional[list[str]] = None) -> None:
     """Manage tmux sessions.
 
     Pass the "--help" argument to any command to see detailed help.
diff --git a/src/tmuxp/cli/debug_info.py b/src/tmuxp/cli/debug_info.py
index 2ce20a2279..f8908a5ba2 100644
--- a/src/tmuxp/cli/debug_info.py
+++ b/src/tmuxp/cli/debug_info.py
@@ -31,7 +31,7 @@ def command_debug_info(
 ) -> None:
     """Entrypoint for ``tmuxp debug-info`` to print debug info to submit with issues."""
 
-    def prepend_tab(strings: t.List[str]) -> t.List[str]:
+    def prepend_tab(strings: list[str]) -> list[str]:
         """Prepend tab to strings in list."""
         return [f"\t{x}" for x in strings]
 
diff --git a/src/tmuxp/cli/freeze.py b/src/tmuxp/cli/freeze.py
index 2feece59fd..b6d4e27617 100644
--- a/src/tmuxp/cli/freeze.py
+++ b/src/tmuxp/cli/freeze.py
@@ -165,7 +165,7 @@ def command_freeze(
     dest = os.path.abspath(os.path.relpath(os.path.expanduser(dest)))
     workspace_format = args.workspace_format
 
-    valid_workspace_formats: t.List[CLIOutputFormatLiteral] = ["json", "yaml"]
+    valid_workspace_formats: list[CLIOutputFormatLiteral] = ["json", "yaml"]
 
     def is_valid_ext(stem: t.Optional[str]) -> "TypeGuard[CLIOutputFormatLiteral]":
         return stem in valid_workspace_formats
@@ -184,15 +184,15 @@ def extract_workspace_format(
 
         workspace_format = extract_workspace_format(dest)
         if not is_valid_ext(workspace_format):
-            _workspace_format = prompt_choices(
+            workspace_format_ = prompt_choices(
                 "Couldn't ascertain one of [{}] from file name. Convert to".format(
                     ", ".join(valid_workspace_formats),
                 ),
-                choices=t.cast(t.List[str], valid_workspace_formats),
+                choices=t.cast("list[str]", valid_workspace_formats),
                 default="yaml",
             )
-            assert is_valid_ext(_workspace_format)
-            workspace_format = _workspace_format
+            assert is_valid_ext(workspace_format_)
+            workspace_format = workspace_format_
 
     if workspace_format == "yaml":
         workspace = configparser.dump(
diff --git a/src/tmuxp/cli/import_config.py b/src/tmuxp/cli/import_config.py
index 3420177f43..1f4127b61d 100644
--- a/src/tmuxp/cli/import_config.py
+++ b/src/tmuxp/cli/import_config.py
@@ -128,7 +128,7 @@ def create_import_subparser(
 class ImportConfigFn(t.Protocol):
     """Typing for import configuration callback function."""
 
-    def __call__(self, workspace_dict: t.Dict[str, t.Any]) -> t.Dict[str, t.Any]:
+    def __call__(self, workspace_dict: dict[str, t.Any]) -> dict[str, t.Any]:
         """Execute tmuxp import function."""
         ...
 
diff --git a/src/tmuxp/cli/load.py b/src/tmuxp/cli/load.py
index e6a5c5aad9..551d9ecf29 100644
--- a/src/tmuxp/cli/load.py
+++ b/src/tmuxp/cli/load.py
@@ -36,7 +36,7 @@ class OptionOverrides(TypedDict):
 class CLILoadNamespace(argparse.Namespace):
     """Typed :class:`argparse.Namespace` for tmuxp load command."""
 
-    workspace_files: t.List[str]
+    workspace_files: list[str]
     socket_name: t.Optional[str]
     socket_path: t.Optional[str]
     tmux_config_file: t.Optional[str]
@@ -47,7 +47,7 @@ class CLILoadNamespace(argparse.Namespace):
     log_file: t.Optional[str]
 
 
-def load_plugins(session_config: t.Dict[str, t.Any]) -> t.List[t.Any]:
+def load_plugins(session_config: dict[str, t.Any]) -> list[t.Any]:
     """Load and return plugins in workspace."""
     plugins = []
     if "plugins" in session_config:
diff --git a/src/tmuxp/cli/utils.py b/src/tmuxp/cli/utils.py
index 6c364bf2bc..83dbaa7085 100644
--- a/src/tmuxp/cli/utils.py
+++ b/src/tmuxp/cli/utils.py
@@ -9,7 +9,7 @@
 if t.TYPE_CHECKING:
     from typing_extensions import TypeAlias
 
-    CLIColour: TypeAlias = t.Union[int, t.Tuple[int, int, int], str]
+    CLIColour: TypeAlias = t.Union[int, tuple[int, int, int], str]
 
 
 logger = logging.getLogger(__name__)
@@ -56,10 +56,10 @@ def prompt(
     `flask-script <https://github.com/techniq/flask-script>`_. See the
     `flask-script license <https://github.com/techniq/flask-script/blob/master/LICENSE>`_.
     """
-    _prompt = name + ((default and f" [{default}]") or "")
-    _prompt += (name.endswith("?") and " ") or ": "
+    prompt_ = name + ((default and f" [{default}]") or "")
+    prompt_ += (name.endswith("?") and " ") or ": "
     while True:
-        rv = input(_prompt) or default
+        rv = input(prompt_) or default
         try:
             if value_proc is not None and callable(value_proc):
                 assert isinstance(rv, str)
@@ -106,11 +106,11 @@ def prompt_bool(
     else:
         prompt_choice = "y/N"
 
-    _prompt = name + f" [{prompt_choice}]"
-    _prompt += (name.endswith("?") and " ") or ": "
+    prompt_ = name + f" [{prompt_choice}]"
+    prompt_ += (name.endswith("?") and " ") or ": "
 
     while True:
-        rv = input(_prompt)
+        rv = input(prompt_)
         if not rv:
             return default
         if rv.lower() in yes_choices:
@@ -126,7 +126,7 @@ def prompt_yes_no(name: str, default: bool = True) -> bool:
 
 def prompt_choices(
     name: str,
-    choices: t.Union[t.List[str], t.Tuple[str, str]],
+    choices: t.Union[list[str], tuple[str, str]],
     default: t.Optional[str] = None,
     no_choice: t.Sequence[str] = ("none",),
 ) -> t.Optional[str]:
@@ -148,8 +148,8 @@ def prompt_choices(
     -------
     str
     """
-    _choices: t.List[str] = []
-    options: t.List[str] = []
+    choices_: list[str] = []
+    options: list[str] = []
 
     for choice in choices:
         if isinstance(choice, str):
@@ -157,7 +157,7 @@ def prompt_choices(
         elif isinstance(choice, tuple):
             options.append(f"{choice} [{choice[0]}]")
             choice = choice[0]
-        _choices.append(choice)
+        choices_.append(choice)
 
     while True:
         rv = prompt(name + " - ({})".format(", ".join(options)), default=default)
@@ -166,7 +166,7 @@ def prompt_choices(
         rv = rv.lower()
         if rv in no_choice:
             return None
-        if rv in _choices:
+        if rv in choices_:
             return rv
 
 
@@ -201,7 +201,7 @@ def strip_ansi(value: str) -> str:
 
 
 def _interpret_color(
-    color: t.Union[int, t.Tuple[int, int, int], str],
+    color: t.Union[int, tuple[int, int, int], str],
     offset: int = 0,
 ) -> str:
     if isinstance(color, int):
diff --git a/src/tmuxp/log.py b/src/tmuxp/log.py
index b841d340ad..57855dcabb 100644
--- a/src/tmuxp/log.py
+++ b/src/tmuxp/log.py
@@ -135,7 +135,7 @@ def format(self, record: logging.LogRecord) -> str:
 
 
 def debug_log_template(
-    self: t.Type[logging.Formatter],
+    self: type[logging.Formatter],
     record: logging.LogRecord,
     stylized: t.Optional[bool] = False,
     **kwargs: t.Any,
diff --git a/src/tmuxp/plugin.py b/src/tmuxp/plugin.py
index adb0ac363d..9920e873f4 100644
--- a/src/tmuxp/plugin.py
+++ b/src/tmuxp/plugin.py
@@ -41,7 +41,7 @@ class VersionConstraints(TypedDict):
         version: t.Union[Version, str]
         vmin: str
         vmax: t.Optional[str]
-        incompatible: t.List[t.Union[t.Any, str]]
+        incompatible: list[t.Union[t.Any, str]]
 
     class TmuxpPluginVersionConstraints(TypedDict):
         """Version constraints for a tmuxp plugin."""
@@ -57,13 +57,13 @@ class Config(t.TypedDict):
     plugin_name: str
     tmux_min_version: str
     tmux_max_version: t.Optional[str]
-    tmux_version_incompatible: t.Optional[t.List[str]]
+    tmux_version_incompatible: t.Optional[list[str]]
     libtmux_min_version: str
     libtmux_max_version: t.Optional[str]
-    libtmux_version_incompatible: t.Optional[t.List[str]]
+    libtmux_version_incompatible: t.Optional[list[str]]
     tmuxp_min_version: str
     tmuxp_max_version: t.Optional[str]
-    tmuxp_version_incompatible: t.Optional[t.List[str]]
+    tmuxp_version_incompatible: t.Optional[list[str]]
 
 
 DEFAULT_CONFIG: "Config" = {
@@ -200,7 +200,7 @@ def _pass_version_check(
         version: t.Union[str, Version],
         vmin: str,
         vmax: t.Optional[str],
-        incompatible: t.List[t.Union[t.Any, str]],
+        incompatible: list[t.Union[t.Any, str]],
     ) -> bool:
         """Provide affirmative if version compatibility is correct."""
         if vmin and version < Version(vmin):
diff --git a/src/tmuxp/shell.py b/src/tmuxp/shell.py
index 9000779564..d7f9094b32 100644
--- a/src/tmuxp/shell.py
+++ b/src/tmuxp/shell.py
@@ -39,10 +39,10 @@ class LaunchImports(t.TypedDict):
         """tmuxp shell launch import mapping."""
 
         libtmux: ModuleType
-        Server: t.Type[Server]
-        Session: t.Type[Session]
-        Window: t.Type[Window]
-        Pane: t.Type[Pane]
+        Server: type[Server]
+        Session: type[Session]
+        Window: type[Window]
+        Pane: type[Pane]
         server: t.Optional["Server"]
         session: t.Optional["Session"]
         window: t.Optional["Window"]
@@ -114,7 +114,7 @@ def detect_best_shell() -> "CLIShellLiteral":
 
 def get_bpython(
     options: "LaunchOptionalImports",
-    extra_args: t.Optional[t.Dict[str, t.Any]] = None,
+    extra_args: t.Optional[dict[str, t.Any]] = None,
 ) -> t.Callable[[], None]:
     """Return bpython shell."""
     if extra_args is None:
@@ -132,7 +132,7 @@ def launch_bpython() -> None:
     return launch_bpython
 
 
-def get_ipython_arguments() -> t.List[str]:
+def get_ipython_arguments() -> list[str]:
     """Return ipython shell args via ``IPYTHON_ARGUMENTS`` environment variables."""
     ipython_args = "IPYTHON_ARGUMENTS"
     return os.environ.get(ipython_args, "").split()
@@ -140,7 +140,7 @@ def get_ipython_arguments() -> t.List[str]:
 
 def get_ipython(
     options: "LaunchOptionalImports",
-    **extra_args: t.Dict[str, t.Any],
+    **extra_args: dict[str, t.Any],
 ) -> t.Any:
     """Return ipython shell."""
     try:
diff --git a/src/tmuxp/workspace/builder.py b/src/tmuxp/workspace/builder.py
index fa4f8330f2..4623ed4b85 100644
--- a/src/tmuxp/workspace/builder.py
+++ b/src/tmuxp/workspace/builder.py
@@ -149,9 +149,9 @@ class WorkspaceBuilder:
 
     def __init__(
         self,
-        session_config: t.Dict[str, t.Any],
+        session_config: dict[str, t.Any],
         server: Server,
-        plugins: t.Optional[t.List[t.Any]] = None,
+        plugins: t.Optional[list[t.Any]] = None,
     ) -> None:
         """Initialize workspace loading.
 
@@ -443,7 +443,7 @@ def iter_create_windows(
     def iter_create_panes(
         self,
         window: Window,
-        window_config: t.Dict[str, t.Any],
+        window_config: dict[str, t.Any],
     ) -> t.Iterator[t.Any]:
         """Return :class:`libtmux.Pane` iterating through window config dict.
 
@@ -479,8 +479,8 @@ def iter_create_panes(
             else:
 
                 def get_pane_start_directory(
-                    pane_config: t.Dict[str, str],
-                    window_config: t.Dict[str, str],
+                    pane_config: dict[str, str],
+                    window_config: dict[str, str],
                 ) -> t.Optional[str]:
                     if "start_directory" in pane_config:
                         return pane_config["start_directory"]
@@ -489,8 +489,8 @@ def get_pane_start_directory(
                     return None
 
                 def get_pane_shell(
-                    pane_config: t.Dict[str, str],
-                    window_config: t.Dict[str, str],
+                    pane_config: dict[str, str],
+                    window_config: dict[str, str],
                 ) -> t.Optional[str]:
                     if "shell" in pane_config:
                         return pane_config["shell"]
@@ -565,7 +565,7 @@ def get_pane_shell(
     def config_after_window(
         self,
         window: Window,
-        window_config: t.Dict[str, t.Any],
+        window_config: dict[str, t.Any],
     ) -> None:
         """Actions to apply to window after window and pane finished.
 
diff --git a/src/tmuxp/workspace/finders.py b/src/tmuxp/workspace/finders.py
index 9e441e75ae..2c202bb0fe 100644
--- a/src/tmuxp/workspace/finders.py
+++ b/src/tmuxp/workspace/finders.py
@@ -21,7 +21,7 @@
 
 def is_workspace_file(
     filename: str,
-    extensions: t.Union["ValidExtensions", t.List["ValidExtensions"], None] = None,
+    extensions: t.Union["ValidExtensions", list["ValidExtensions"], None] = None,
 ) -> bool:
     """
     Return True if file has a valid workspace file type.
@@ -45,8 +45,8 @@ def is_workspace_file(
 
 def in_dir(
     workspace_dir: t.Union[pathlib.Path, str, None] = None,
-    extensions: t.Optional[t.List["ValidExtensions"]] = None,
-) -> t.List[str]:
+    extensions: t.Optional[list["ValidExtensions"]] = None,
+) -> list[str]:
     """
     Return a list of workspace_files in ``workspace_dir``.
 
@@ -74,7 +74,7 @@ def in_dir(
     ]
 
 
-def in_cwd() -> t.List[str]:
+def in_cwd() -> list[str]:
     """
     Return list of workspace_files in current working directory.
 
@@ -187,7 +187,7 @@ def find_workspace_file(
                 ]
                 if exists(x)
             ]
-            if not len(candidates):
+            if not candidates:
                 file_error = (
                     "workspace-file not found "
                     + f"in workspace dir (yaml/yml/json) {workspace_dir} for name"
diff --git a/src/tmuxp/workspace/freezer.py b/src/tmuxp/workspace/freezer.py
index e782ccec2c..fba5103a73 100644
--- a/src/tmuxp/workspace/freezer.py
+++ b/src/tmuxp/workspace/freezer.py
@@ -9,7 +9,7 @@
     from libtmux.window import Window
 
 
-def inline(workspace_dict: t.Dict[str, t.Any]) -> t.Any:
+def inline(workspace_dict: dict[str, t.Any]) -> t.Any:
     """Return workspace with inlined shorthands. Opposite of :meth:`loader.expand`.
 
     Parameters
@@ -50,7 +50,7 @@ def inline(workspace_dict: t.Dict[str, t.Any]) -> t.Any:
     return workspace_dict
 
 
-def freeze(session: Session) -> t.Dict[str, t.Any]:
+def freeze(session: Session) -> dict[str, t.Any]:
     """Freeze live tmux session into a tmuxp workspacee.
 
     Parameters
@@ -63,13 +63,13 @@ def freeze(session: Session) -> t.Dict[str, t.Any]:
     dict
         tmuxp compatible workspace
     """
-    session_config: t.Dict[str, t.Any] = {
+    session_config: dict[str, t.Any] = {
         "session_name": session.session_name,
         "windows": [],
     }
 
     for window in session.windows:
-        window_config: t.Dict[str, t.Any] = {
+        window_config: dict[str, t.Any] = {
             "options": window.show_window_options(),
             "window_name": window.name,
             "layout": window.window_layout,
@@ -88,7 +88,7 @@ def pane_has_same_path(window: "Window", pane: Pane) -> bool:
             window_config["start_directory"] = window.panes[0].pane_current_path
 
         for pane in window.panes:
-            pane_config: t.Union[str, t.Dict[str, t.Any]] = {"shell_command": []}
+            pane_config: t.Union[str, dict[str, t.Any]] = {"shell_command": []}
             assert isinstance(pane_config, dict)
 
             if "start_directory" not in window_config and pane.pane_current_path:
diff --git a/src/tmuxp/workspace/importers.py b/src/tmuxp/workspace/importers.py
index 9f4b1e4b16..2ee9c7880f 100644
--- a/src/tmuxp/workspace/importers.py
+++ b/src/tmuxp/workspace/importers.py
@@ -3,7 +3,7 @@
 import typing as t
 
 
-def import_tmuxinator(workspace_dict: t.Dict[str, t.Any]) -> t.Dict[str, t.Any]:
+def import_tmuxinator(workspace_dict: dict[str, t.Any]) -> dict[str, t.Any]:
     """Return tmuxp workspace from a `tmuxinator`_ yaml workspace.
 
     .. _tmuxinator: https://github.com/aziz/tmuxinator
@@ -100,7 +100,7 @@ def import_tmuxinator(workspace_dict: t.Dict[str, t.Any]) -> t.Dict[str, t.Any]:
     return tmuxp_workspace
 
 
-def import_teamocil(workspace_dict: t.Dict[str, t.Any]) -> t.Dict[str, t.Any]:
+def import_teamocil(workspace_dict: dict[str, t.Any]) -> dict[str, t.Any]:
     """Return tmuxp workspace from a `teamocil`_ yaml workspace.
 
     .. _teamocil: https://github.com/remiprev/teamocil
diff --git a/src/tmuxp/workspace/loader.py b/src/tmuxp/workspace/loader.py
index 58da0ee91a..bf9c7c098a 100644
--- a/src/tmuxp/workspace/loader.py
+++ b/src/tmuxp/workspace/loader.py
@@ -26,7 +26,7 @@ def expandshell(value: str) -> str:
     return os.path.expandvars(os.path.expanduser(value))  # NOQA: PTH111
 
 
-def expand_cmd(p: t.Dict[str, t.Any]) -> t.Dict[str, t.Any]:
+def expand_cmd(p: dict[str, t.Any]) -> dict[str, t.Any]:
     """Resolve shell variables and expand shorthands in a tmuxp config mapping."""
     if isinstance(p, str):
         p = {"shell_command": [p]}
@@ -64,10 +64,10 @@ def expand_cmd(p: t.Dict[str, t.Any]) -> t.Dict[str, t.Any]:
 
 
 def expand(
-    workspace_dict: t.Dict[str, t.Any],
+    workspace_dict: dict[str, t.Any],
     cwd: t.Optional[t.Union[pathlib.Path, str]] = None,
     parent: t.Optional[t.Any] = None,
-) -> t.Dict[str, t.Any]:
+) -> dict[str, t.Any]:
     """Resolve workspace variables and expand shorthand style / inline properties.
 
     This is necessary to keep the code in the :class:`WorkspaceBuilder` clean
@@ -186,7 +186,7 @@ def expand(
     return workspace_dict
 
 
-def trickle(workspace_dict: t.Dict[str, t.Any]) -> t.Dict[str, t.Any]:
+def trickle(workspace_dict: dict[str, t.Any]) -> dict[str, t.Any]:
     """Return a dict with "trickled down" / inherited workspace values.
 
     This will only work if workspace has been expanded to full form with
diff --git a/tests/cli/test_cli.py b/tests/cli/test_cli.py
index 4ad5d28204..2c271d39e2 100644
--- a/tests/cli/test_cli.py
+++ b/tests/cli/test_cli.py
@@ -37,7 +37,7 @@ def test_creates_config_dir_not_exists(tmp_path: pathlib.Path) -> None:
     ],
 )
 def test_help(
-    cli_args: t.List[str],
+    cli_args: list[str],
     tmp_path: pathlib.Path,
     monkeypatch: pytest.MonkeyPatch,
     capsys: pytest.CaptureFixture[str],
diff --git a/tests/cli/test_convert.py b/tests/cli/test_convert.py
index 5e792a473e..d9de79ede8 100644
--- a/tests/cli/test_convert.py
+++ b/tests/cli/test_convert.py
@@ -4,7 +4,6 @@
 import io
 import json
 import pathlib
-import typing as t
 
 import pytest
 
@@ -22,7 +21,7 @@
     ],
 )
 def test_convert(
-    cli_args: t.List[str],
+    cli_args: list[str],
     tmp_path: pathlib.Path,
     monkeypatch: pytest.MonkeyPatch,
 ) -> None:
@@ -62,7 +61,7 @@ def test_convert(
     ],
 )
 def test_convert_json(
-    cli_args: t.List[str],
+    cli_args: list[str],
     tmp_path: pathlib.Path,
     monkeypatch: pytest.MonkeyPatch,
 ) -> None:
diff --git a/tests/cli/test_freeze.py b/tests/cli/test_freeze.py
index 0dc56c48e6..0d2d184ba6 100644
--- a/tests/cli/test_freeze.py
+++ b/tests/cli/test_freeze.py
@@ -31,8 +31,8 @@
 )
 def test_freeze(
     server: "Server",
-    cli_args: t.List[str],
-    inputs: t.List[str],
+    cli_args: list[str],
+    inputs: list[str],
     tmp_path: pathlib.Path,
     monkeypatch: pytest.MonkeyPatch,
 ) -> None:
@@ -83,8 +83,8 @@ def test_freeze(
 )
 def test_freeze_overwrite(
     server: "Server",
-    cli_args: t.List[str],
-    inputs: t.List[str],
+    cli_args: list[str],
+    inputs: list[str],
     tmp_path: pathlib.Path,
     monkeypatch: pytest.MonkeyPatch,
 ) -> None:
diff --git a/tests/cli/test_import.py b/tests/cli/test_import.py
index 1e94d4e2ff..2e1e1497f9 100644
--- a/tests/cli/test_import.py
+++ b/tests/cli/test_import.py
@@ -3,7 +3,6 @@
 import contextlib
 import io
 import pathlib
-import typing as t
 
 import pytest
 
@@ -13,7 +12,7 @@
 
 @pytest.mark.parametrize("cli_args", [(["import"])])
 def test_import(
-    cli_args: t.List[str],
+    cli_args: list[str],
     tmp_path: pathlib.Path,
     monkeypatch: pytest.MonkeyPatch,
     capsys: pytest.CaptureFixture[str],
@@ -43,8 +42,8 @@ def test_import(
     ],
 )
 def test_import_teamocil(
-    cli_args: t.List[str],
-    inputs: t.List[str],
+    cli_args: list[str],
+    inputs: list[str],
     tmp_path: pathlib.Path,
     monkeypatch: pytest.MonkeyPatch,
 ) -> None:
@@ -90,8 +89,8 @@ def test_import_teamocil(
     ],
 )
 def test_import_tmuxinator(
-    cli_args: t.List[str],
-    inputs: t.List[str],
+    cli_args: list[str],
+    inputs: list[str],
     tmp_path: pathlib.Path,
     monkeypatch: pytest.MonkeyPatch,
 ) -> None:
diff --git a/tests/cli/test_load.py b/tests/cli/test_load.py
index 0a1f0dd05d..fd04f48762 100644
--- a/tests/cli/test_load.py
+++ b/tests/cli/test_load.py
@@ -187,7 +187,7 @@ def test_load_symlinked_workspace(
 if t.TYPE_CHECKING:
     from typing_extensions import TypeAlias
 
-    ExpectedOutput: TypeAlias = t.Optional[t.Union[str, t.List[str]]]
+    ExpectedOutput: TypeAlias = t.Optional[t.Union[str, list[str]]]
 
 
 class CLILoadFixture(t.NamedTuple):
@@ -197,9 +197,9 @@ class CLILoadFixture(t.NamedTuple):
     test_id: str
 
     # test params
-    cli_args: t.List[t.Union[str, t.List[str]]]
-    config_paths: t.List[str]
-    session_names: t.List[str]
+    cli_args: list[t.Union[str, list[str]]]
+    config_paths: list[str]
+    session_names: list[str]
     expected_exit_code: int
     expected_in_out: "ExpectedOutput" = None
     expected_not_in_out: "ExpectedOutput" = None
@@ -207,7 +207,7 @@ class CLILoadFixture(t.NamedTuple):
     expected_not_in_err: "ExpectedOutput" = None
 
 
-TEST_LOAD_FIXTURES: t.List[CLILoadFixture] = [
+TEST_LOAD_FIXTURES: list[CLILoadFixture] = [
     CLILoadFixture(
         test_id="dir-relative-dot-samedir",
         cli_args=["load", "."],
@@ -294,9 +294,9 @@ def test_load(
     capsys: pytest.CaptureFixture[str],
     monkeypatch: pytest.MonkeyPatch,
     test_id: str,
-    cli_args: t.List[str],
-    config_paths: t.List[str],
-    session_names: t.List[str],
+    cli_args: list[str],
+    config_paths: list[str],
+    session_names: list[str],
     expected_exit_code: int,
     expected_in_out: "ExpectedOutput",
     expected_not_in_out: "ExpectedOutput",
@@ -362,7 +362,7 @@ def test_regression_00132_session_name_with_dots(
     [["load", ".", "-d"], ["load", ".tmuxp.yaml", "-d"]],
 )
 def test_load_zsh_autotitle_warning(
-    cli_args: t.List[str],
+    cli_args: list[str],
     tmp_path: pathlib.Path,
     monkeypatch: pytest.MonkeyPatch,
     capsys: pytest.CaptureFixture[str],
@@ -422,7 +422,7 @@ def test_load_zsh_autotitle_warning(
     ],
 )
 def test_load_log_file(
-    cli_args: t.List[str],
+    cli_args: list[str],
     tmp_path: pathlib.Path,
     monkeypatch: pytest.MonkeyPatch,
     capsys: pytest.CaptureFixture[str],
@@ -488,8 +488,8 @@ def test_load_plugins(
 )
 def test_load_plugins_version_fail_skip(
     monkeypatch_plugin_test_packages: None,
-    cli_args: t.List[str],
-    inputs: t.List[str],
+    cli_args: list[str],
+    inputs: list[str],
     capsys: pytest.CaptureFixture[str],
 ) -> None:
     """Test tmuxp load with plugins failing version constraints can continue."""
@@ -512,8 +512,8 @@ def test_load_plugins_version_fail_skip(
 )
 def test_load_plugins_version_fail_no_skip(
     monkeypatch_plugin_test_packages: None,
-    cli_args: t.List[str],
-    inputs: t.List[str],
+    cli_args: list[str],
+    inputs: list[str],
     monkeypatch: pytest.MonkeyPatch,
     capsys: pytest.CaptureFixture[str],
 ) -> None:
@@ -534,7 +534,7 @@ def test_load_plugins_version_fail_no_skip(
 )
 def test_load_plugins_plugin_missing(
     monkeypatch_plugin_test_packages: None,
-    cli_args: t.List[str],
+    cli_args: list[str],
     capsys: pytest.CaptureFixture[str],
 ) -> None:
     """Test tmuxp load with plugins missing raise an error."""
diff --git a/tests/cli/test_shell.py b/tests/cli/test_shell.py
index 39f7e7d694..6690b2a333 100644
--- a/tests/cli/test_shell.py
+++ b/tests/cli/test_shell.py
@@ -22,13 +22,13 @@ class CLIShellFixture(t.NamedTuple):
     test_id: str
 
     # test params
-    cli_args: t.List[str]
-    inputs: t.List[t.Any]
-    env: t.Dict[str, str]
+    cli_args: list[str]
+    inputs: list[t.Any]
+    env: dict[str, str]
     expected_output: str
 
 
-TEST_SHELL_FIXTURES: t.List[CLIShellFixture] = [
+TEST_SHELL_FIXTURES: list[CLIShellFixture] = [
     CLIShellFixture(
         test_id="print-socket-name",
         cli_args=["-L{SOCKET_NAME}", "-c", "print(str(server.socket_name))"],
@@ -108,11 +108,11 @@ class CLIShellFixture(t.NamedTuple):
     ids=[test.test_id for test in TEST_SHELL_FIXTURES],
 )
 def test_shell(
-    cli_cmd: t.List[str],
+    cli_cmd: list[str],
     test_id: str,
-    cli_args: t.List[str],
-    inputs: t.List[t.Any],
-    env: t.Dict[str, str],
+    cli_args: list[str],
+    inputs: list[t.Any],
+    env: dict[str, str],
     expected_output: str,
     server: "Server",
     session: Session,
@@ -196,14 +196,14 @@ def test_shell(
     ],
 )
 def test_shell_target_missing(
-    cli_cmd: t.List[str],
-    cli_args: t.List[str],
-    inputs: t.List[t.Any],
-    env: t.Dict[t.Any, t.Any],
-    template_ctx: t.Dict[str, str],
+    cli_cmd: list[str],
+    cli_args: list[str],
+    inputs: list[t.Any],
+    env: dict[t.Any, t.Any],
+    template_ctx: dict[str, str],
     exception: t.Union[
-        t.Type[exc.TmuxpException],
-        t.Type[subprocess.CalledProcessError],
+        type[exc.TmuxpException],
+        type[subprocess.CalledProcessError],
     ],
     message: str,
     socket_name: str,
@@ -279,10 +279,10 @@ def test_shell_target_missing(
     ],
 )
 def test_shell_interactive(
-    cli_cmd: t.List[str],
-    cli_args: t.List[str],
-    inputs: t.List[t.Any],
-    env: t.Dict[str, str],
+    cli_cmd: list[str],
+    cli_args: list[str],
+    inputs: list[t.Any],
+    env: dict[str, str],
     message: str,
     server: "Server",
     session: Session,
diff --git a/tests/fixtures/pluginsystem/partials/_types.py b/tests/fixtures/pluginsystem/partials/_types.py
index d275ad8982..77d2328cd5 100644
--- a/tests/fixtures/pluginsystem/partials/_types.py
+++ b/tests/fixtures/pluginsystem/partials/_types.py
@@ -10,8 +10,6 @@
 ...
 """
 
-import typing as t
-
 from typing_extensions import NotRequired, TypedDict
 
 
@@ -26,10 +24,10 @@ class PluginTestConfigSchema(TypedDict):
     plugin_name: NotRequired[str]
     tmux_min_version: NotRequired[str]
     tmux_max_version: NotRequired[str]
-    tmux_version_incompatible: NotRequired[t.List[str]]
+    tmux_version_incompatible: NotRequired[list[str]]
     libtmux_min_version: NotRequired[str]
     libtmux_max_version: NotRequired[str]
-    libtmux_version_incompatible: NotRequired[t.List[str]]
+    libtmux_version_incompatible: NotRequired[list[str]]
     tmuxp_min_version: NotRequired[str]
     tmuxp_max_version: NotRequired[str]
-    tmuxp_version_incompatible: NotRequired[t.List[str]]
+    tmuxp_version_incompatible: NotRequired[list[str]]
diff --git a/tests/fixtures/utils.py b/tests/fixtures/utils.py
index 9e6b454bf6..81fd07cf89 100644
--- a/tests/fixtures/utils.py
+++ b/tests/fixtures/utils.py
@@ -7,23 +7,23 @@
 
 
 def get_workspace_file(
-    _file: t.Union[str, pathlib.Path],
+    file: t.Union[str, pathlib.Path],
 ) -> pathlib.Path:
     """Return fixture data, relative to __file__."""
-    if isinstance(_file, str):
-        _file = pathlib.Path(_file)
+    if isinstance(file, str):
+        file = pathlib.Path(file)
 
-    return FIXTURE_PATH / _file
+    return FIXTURE_PATH / file
 
 
 def read_workspace_file(
-    _file: t.Union[pathlib.Path, str],
+    file: t.Union[pathlib.Path, str],
 ) -> str:
     """Return fixture data, relative to __file__."""
-    if isinstance(_file, str):
-        _file = pathlib.Path(_file)
+    if isinstance(file, str):
+        file = pathlib.Path(file)
 
-    return get_workspace_file(_file).open().read()
+    return get_workspace_file(file).open().read()
 
 
 def write_config(
diff --git a/tests/fixtures/workspace/expand1.py b/tests/fixtures/workspace/expand1.py
index 75db0e7f48..75d5d06c00 100644
--- a/tests/fixtures/workspace/expand1.py
+++ b/tests/fixtures/workspace/expand1.py
@@ -33,7 +33,7 @@
 }
 
 
-def after_workspace() -> t.Dict[str, t.Any]:
+def after_workspace() -> dict[str, t.Any]:
     """After expansion of shorthand style."""
     return {
         "session_name": "sample workspace",
diff --git a/tests/fixtures/workspace/shell_command_before.py b/tests/fixtures/workspace/shell_command_before.py
index a0f80510c5..10b74518dd 100644
--- a/tests/fixtures/workspace/shell_command_before.py
+++ b/tests/fixtures/workspace/shell_command_before.py
@@ -40,7 +40,7 @@
 }
 
 
-def config_expanded() -> t.Dict[str, t.Any]:
+def config_expanded() -> dict[str, t.Any]:
     """Return expanded configuration for shell_command_before example."""
     return {  # shell_command_before is string in some areas
         "session_name": "sample workspace",
@@ -93,7 +93,7 @@ def config_expanded() -> t.Dict[str, t.Any]:
     }
 
 
-def config_after() -> t.Dict[str, t.Any]:
+def config_after() -> dict[str, t.Any]:
     """Return expected configuration for shell_command_before example."""
     return {  # shell_command_before is string in some areas
         "session_name": "sample workspace",
diff --git a/tests/workspace/test_builder.py b/tests/workspace/test_builder.py
index 801b462d5a..21ba3c8e59 100644
--- a/tests/workspace/test_builder.py
+++ b/tests/workspace/test_builder.py
@@ -94,12 +94,12 @@ def test_focus_pane_index(session: Session) -> None:
 
     assert session.active_window.name == "focused window"
 
-    _pane_base_index = session.active_window.show_window_option(
+    pane_base_index_ = session.active_window.show_window_option(
         "pane-base-index",
         g=True,
     )
-    assert isinstance(_pane_base_index, int)
-    pane_base_index = int(_pane_base_index)
+    assert isinstance(pane_base_index_, int)
+    pane_base_index = int(pane_base_index_)
 
     pane_base_index = 0 if not pane_base_index else int(pane_base_index)
 
@@ -215,9 +215,9 @@ def f(p: Pane, buffer_name: str, assertCase: AssertCallbackProtocol) -> bool:
 
             return assertCase(sent_cmd, history_cmd)
 
-        _f = functools.partial(f, p=p, buffer_name=buffer_name, assertCase=assertCase)
+        f_ = functools.partial(f, p=p, buffer_name=buffer_name, assertCase=assertCase)
 
-        assert retry_until(_f), f"Unknown sent command: [{sent_cmd}] in {assertCase}"
+        assert retry_until(f_), f"Unknown sent command: [{sent_cmd}] in {assertCase}"
 
 
 def test_session_options(session: Session) -> None:
@@ -230,13 +230,13 @@ def test_session_options(session: Session) -> None:
     builder = WorkspaceBuilder(session_config=workspace, server=session.server)
     builder.build(session=session)
 
-    _default_shell = session.show_option("default-shell")
-    assert isinstance(_default_shell, str)
-    assert "/bin/sh" in _default_shell
+    default_shell = session.show_option("default-shell")
+    assert isinstance(default_shell, str)
+    assert "/bin/sh" in default_shell
 
-    _default_command = session.show_option("default-command")
-    assert isinstance(_default_command, str)
-    assert "/bin/sh" in _default_command
+    default_command = session.show_option("default-command")
+    assert isinstance(default_command, str)
+    assert "/bin/sh" in default_command
 
 
 def test_global_options(session: Session) -> None:
@@ -249,9 +249,9 @@ def test_global_options(session: Session) -> None:
     builder = WorkspaceBuilder(session_config=workspace, server=session.server)
     builder.build(session=session)
 
-    _status_position = session.show_option("status-position", _global=True)
-    assert isinstance(_status_position, str)
-    assert "top" in _status_position
+    status_position = session.show_option("status-position", _global=True)
+    assert isinstance(status_position, str)
+    assert "top" in status_position
     assert session.show_option("repeat-time", _global=True) == 493
 
 
@@ -275,9 +275,9 @@ def test_global_session_env_options(
     builder = WorkspaceBuilder(session_config=workspace, server=session.server)
     builder.build(session=session)
 
-    _visual_silence = session.show_option("visual-silence", _global=True)
-    assert isinstance(_visual_silence, str)
-    assert visual_silence in _visual_silence
+    visual_silence_ = session.show_option("visual-silence", _global=True)
+    assert isinstance(visual_silence_, str)
+    assert visual_silence in visual_silence_
     assert repeat_time == session.show_option("repeat-time")
     assert main_pane_height == session.active_window.show_window_option(
         "main-pane-height",
@@ -376,9 +376,9 @@ def test_window_shell(
         def f(w: Window) -> bool:
             return w.window_name != "top"
 
-        _f = functools.partial(f, w=w)
+        f_ = functools.partial(f, w=w)
 
-        retry_until(_f)
+        retry_until(f_)
 
         assert w.name != "top"
 
@@ -592,10 +592,10 @@ def f(path: str, p: Pane) -> bool:
                     pane_path is not None and path in pane_path
                 ) or pane_path == path
 
-            _f = functools.partial(f, path=path, p=p)
+            f_ = functools.partial(f, path=path, p=p)
 
             # handle case with OS X adding /private/ to /tmp/ paths
-            assert retry_until(_f)
+            assert retry_until(f_)
 
 
 def test_start_directory_relative(session: Session, tmp_path: pathlib.Path) -> None:
@@ -647,10 +647,10 @@ def f(path: str, p: Pane) -> bool:
                     pane_path is not None and path in pane_path
                 ) or pane_path == path
 
-            _f = functools.partial(f, path=path, p=p)
+            f_ = functools.partial(f, path=path, p=p)
 
             # handle case with OS X adding /private/ to /tmp/ paths
-            assert retry_until(_f)
+            assert retry_until(f_)
 
 
 @pytest.mark.skipif(
@@ -726,9 +726,9 @@ def f(pane_path: str, p: Pane) -> bool:
                 p.refresh()
                 return p.pane_current_path == pane_path
 
-            _f = functools.partial(f, pane_path=pane_path, p=p)
+            f_ = functools.partial(f, pane_path=pane_path, p=p)
 
-            assert retry_until(_f)
+            assert retry_until(f_)
 
 
 def test_window_index(
@@ -1406,10 +1406,10 @@ def f(path: str, p: Pane) -> bool:
             pane_path = p.pane_current_path
             return (pane_path is not None and path in pane_path) or pane_path == path
 
-        _f = functools.partial(f, path=path, p=p)
+        f_ = functools.partial(f, path=path, p=p)
 
         # handle case with OS X adding /private/ to /tmp/ paths
-        assert retry_until(_f)
+        assert retry_until(f_)
 
 
 @pytest.mark.skipif(
@@ -1463,7 +1463,7 @@ class DefaultSizeNamespaceFixture(t.NamedTuple):
     # test params
     TMUXP_DEFAULT_SIZE: t.Optional[str]
     raises: bool
-    confoverrides: t.Dict[str, t.Any]
+    confoverrides: dict[str, t.Any]
 
 
 DEFAULT_SIZE_FIXTURES = [
@@ -1500,7 +1500,7 @@ def test_issue_800_default_size_many_windows(
     test_id: str,
     TMUXP_DEFAULT_SIZE: t.Optional[str],
     raises: bool,
-    confoverrides: t.Dict[str, t.Any],
+    confoverrides: dict[str, t.Any],
 ) -> None:
     """Recreate default-size issue.
 
diff --git a/tests/workspace/test_config.py b/tests/workspace/test_config.py
index 66adee78d6..f04cd1d93b 100644
--- a/tests/workspace/test_config.py
+++ b/tests/workspace/test_config.py
@@ -14,7 +14,7 @@
     from tests.fixtures.structures import WorkspaceTestData
 
 
-def load_workspace(path: t.Union[str, pathlib.Path]) -> t.Dict[str, t.Any]:
+def load_workspace(path: t.Union[str, pathlib.Path]) -> dict[str, t.Any]:
     """Load tmuxp workspace configuration from file."""
     return ConfigReader._from_file(
         pathlib.Path(path) if isinstance(path, str) else path,
diff --git a/tests/workspace/test_import_teamocil.py b/tests/workspace/test_import_teamocil.py
index 8ae913c61e..347fe26627 100644
--- a/tests/workspace/test_import_teamocil.py
+++ b/tests/workspace/test_import_teamocil.py
@@ -36,8 +36,8 @@
 )
 def test_config_to_dict(
     teamocil_yaml: str,
-    teamocil_dict: t.Dict[str, t.Any],
-    tmuxp_dict: t.Dict[str, t.Any],
+    teamocil_dict: dict[str, t.Any],
+    tmuxp_dict: dict[str, t.Any],
 ) -> None:
     """Test exporting teamocil configuration to dictionary."""
     yaml_to_dict = config_reader.ConfigReader._load(
@@ -53,9 +53,9 @@ def test_config_to_dict(
 
 @pytest.fixture(scope="module")
 def multisession_config() -> (
-    t.Dict[
+    dict[
         str,
-        t.Dict[str, t.Any],
+        dict[str, t.Any],
     ]
 ):
     """Return loaded multisession teamocil config as a dictionary.
@@ -65,7 +65,7 @@ def multisession_config() -> (
     """
     teamocil_yaml_file = fixtures.layouts.teamocil_yaml_file
     test_config = config_reader.ConfigReader._from_file(teamocil_yaml_file)
-    teamocil_dict: t.Dict[str, t.Any] = fixtures.layouts.teamocil_dict
+    teamocil_dict: dict[str, t.Any] = fixtures.layouts.teamocil_dict
 
     assert test_config == teamocil_dict
     return teamocil_dict
@@ -88,8 +88,8 @@ def multisession_config() -> (
 )
 def test_multisession_config(
     session_name: str,
-    expected: t.Dict[str, t.Any],
-    multisession_config: t.Dict[str, t.Any],
+    expected: dict[str, t.Any],
+    multisession_config: dict[str, t.Any],
 ) -> None:
     """Test importing teamocil multisession configuration."""
     # teamocil can fit multiple sessions in a config
diff --git a/tests/workspace/test_import_tmuxinator.py b/tests/workspace/test_import_tmuxinator.py
index d5dfe3ba2e..086c382f83 100644
--- a/tests/workspace/test_import_tmuxinator.py
+++ b/tests/workspace/test_import_tmuxinator.py
@@ -31,8 +31,8 @@
 )
 def test_config_to_dict(
     tmuxinator_yaml: str,
-    tmuxinator_dict: t.Dict[str, t.Any],
-    tmuxp_dict: t.Dict[str, t.Any],
+    tmuxinator_dict: dict[str, t.Any],
+    tmuxp_dict: dict[str, t.Any],
 ) -> None:
     """Test exporting tmuxinator configuration to dictionary."""
     yaml_to_dict = ConfigReader._load(fmt="yaml", content=tmuxinator_yaml)