diff --git a/.pre-commit-config.yaml b/.pre-commit-config.yaml
index 4cf5687..27b394d 100644
--- a/.pre-commit-config.yaml
+++ b/.pre-commit-config.yaml
@@ -71,4 +71,5 @@ repos:
   hooks:
   - id: mypy
     additional_dependencies: [types-all]
+    files: babelizer/.*\.py$
     exclude: ^babelizer/data
diff --git a/babelizer/_datadir.py b/babelizer/_datadir.py
index 02ceff7..afb08e3 100644
--- a/babelizer/_datadir.py
+++ b/babelizer/_datadir.py
@@ -1,3 +1,5 @@
+from __future__ import annotations
+
 import sys
 
 if sys.version_info >= (3, 12):  # pragma: no cover (PY12+)
diff --git a/babelizer/_files/bmi_py.py b/babelizer/_files/bmi_py.py
index 33e10cf..1d00e5b 100644
--- a/babelizer/_files/bmi_py.py
+++ b/babelizer/_files/bmi_py.py
@@ -1,11 +1,13 @@
+from __future__ import annotations
+
 import os
+from collections.abc import Mapping
+from typing import Any
 
 
-def render(plugin_metadata) -> str:
+def render(plugin_metadata: Mapping[str, Any]) -> str:
     """Render _bmi.py."""
-    languages = {
-        library["language"] for library in plugin_metadata._meta["library"].values()
-    }
+    languages = {library["language"] for library in plugin_metadata["library"].values()}
     assert len(languages) == 1
     language = languages.pop()
 
@@ -15,22 +17,18 @@ def render(plugin_metadata) -> str:
         return _render_bmi_c(plugin_metadata)
 
 
-def _render_bmi_c(plugin_metadata) -> str:
+def _render_bmi_c(plugin_metadata: Mapping[str, Any]) -> str:
     """Render _bmi.py for a non-python library."""
-    languages = [
-        library["language"] for library in plugin_metadata._meta["library"].values()
-    ]
+    languages = [library["language"] for library in plugin_metadata["library"].values()]
     language = languages[0]
     assert language in ("c", "c++", "fortran")
 
     imports = [
-        f"from {plugin_metadata.get('package', 'name')}.lib import {cls}"
-        for cls in plugin_metadata._meta["library"]
+        f"from {plugin_metadata['package']['name']}.lib import {cls}"
+        for cls in plugin_metadata["library"]
     ]
 
-    names = [
-        f"    {cls!r},".replace("'", '"') for cls in plugin_metadata._meta["library"]
-    ]
+    names = [f"    {cls!r},".replace("'", '"') for cls in plugin_metadata["library"]]
 
     return f"""\
 {os.linesep.join(sorted(imports))}
@@ -41,11 +39,9 @@ def _render_bmi_c(plugin_metadata) -> str:
 """
 
 
-def _render_bmi_py(plugin_metadata) -> str:
+def _render_bmi_py(plugin_metadata: Mapping[str, Any]) -> str:
     """Render _bmi.py for a python library."""
-    languages = [
-        library["language"] for library in plugin_metadata._meta["library"].values()
-    ]
+    languages = [library["language"] for library in plugin_metadata["library"].values()]
     language = languages[0]
     assert language == "python"
 
@@ -60,7 +56,7 @@ def _render_bmi_py(plugin_metadata) -> str:
 
     imports = [
         f"from {component['library']} import {component['entry_point']} as {cls}"
-        for cls, component in plugin_metadata._meta["library"].items()
+        for cls, component in plugin_metadata["library"].items()
     ]
 
     rename = [
@@ -70,12 +66,10 @@ def _render_bmi_py(plugin_metadata) -> str:
 """.replace(
             "'", '"'
         )
-        for cls in plugin_metadata._meta["library"]
+        for cls in plugin_metadata["library"]
     ]
 
-    names = [
-        f"    {cls!r},".replace("'", '"') for cls in plugin_metadata._meta["library"]
-    ]
+    names = [f"    {cls!r},".replace("'", '"') for cls in plugin_metadata["library"]]
 
     return f"""\
 {header}
diff --git a/babelizer/_files/gitignore.py b/babelizer/_files/gitignore.py
index 4d361f5..1296106 100644
--- a/babelizer/_files/gitignore.py
+++ b/babelizer/_files/gitignore.py
@@ -1,7 +1,11 @@
+from __future__ import annotations
+
 import os
+from collections.abc import Mapping
+from typing import Any
 
 
-def render(plugin_metadata) -> str:
+def render(plugin_metadata: Mapping[str, Any]) -> str:
     """Render a .gitignore file."""
     package_name = plugin_metadata["package"]["name"]
 
diff --git a/babelizer/_files/init_py.py b/babelizer/_files/init_py.py
index 963c999..5999df8 100644
--- a/babelizer/_files/init_py.py
+++ b/babelizer/_files/init_py.py
@@ -1,19 +1,20 @@
+from __future__ import annotations
+
 import os
+from collections.abc import Mapping
+from typing import Any
 
 
-def render(plugin_metadata) -> str:
+def render(plugin_metadata: Mapping[str, Any]) -> str:
     """Render __init__.py."""
-    package_name = plugin_metadata.get("package", "name")
+    package_name = plugin_metadata["package"]["name"]
 
     imports = [f"from {package_name}._version import __version__"]
     imports += [
-        f"from {package_name}._bmi import {cls}"
-        for cls in plugin_metadata._meta["library"]
+        f"from {package_name}._bmi import {cls}" for cls in plugin_metadata["library"]
     ]
 
-    names = [
-        f"    {cls!r},".replace("'", '"') for cls in plugin_metadata._meta["library"]
-    ]
+    names = [f"    {cls!r},".replace("'", '"') for cls in plugin_metadata["library"]]
 
     return f"""\
 {os.linesep.join(sorted(imports))}
diff --git a/babelizer/_files/lib_init_py.py b/babelizer/_files/lib_init_py.py
index 3c9227b..269b655 100644
--- a/babelizer/_files/lib_init_py.py
+++ b/babelizer/_files/lib_init_py.py
@@ -1,17 +1,19 @@
+from __future__ import annotations
+
 import os
+from collections.abc import Mapping
+from typing import Any
 
 
-def render(plugin_metadata) -> str:
+def render(plugin_metadata: Mapping[str, Any]) -> str:
     """Render lib/__init__.py."""
-    package_name = plugin_metadata.get("package", "name")
+    package_name = plugin_metadata["package"]["name"]
     imports = [
         f"from {package_name}.lib.{cls.lower()} import {cls}"
-        for cls in plugin_metadata._meta["library"]
+        for cls in plugin_metadata["library"]
     ]
 
-    names = [
-        f"    {cls!r},".replace("'", '"') for cls in plugin_metadata._meta["library"]
-    ]
+    names = [f"    {cls!r},".replace("'", '"') for cls in plugin_metadata["library"]]
 
     return f"""\
 {os.linesep.join(sorted(imports))}
diff --git a/babelizer/_files/license_rst.py b/babelizer/_files/license_rst.py
index a18ebb1..1d5bc49 100644
--- a/babelizer/_files/license_rst.py
+++ b/babelizer/_files/license_rst.py
@@ -1,7 +1,11 @@
+from __future__ import annotations
+
+from collections.abc import Mapping
 from datetime import datetime
+from typing import Any
 
 
-def render(plugin_metadata) -> str:
+def render(plugin_metadata: Mapping[str, Any]) -> str:
     """Render LICENSE.rst."""
     license_name = plugin_metadata["info"]["package_license"]
     kwds = {
diff --git a/babelizer/_files/meson_build.py b/babelizer/_files/meson_build.py
index ac725bb..4996e3d 100644
--- a/babelizer/_files/meson_build.py
+++ b/babelizer/_files/meson_build.py
@@ -1,3 +1,5 @@
+from __future__ import annotations
+
 import os
 from collections import defaultdict
 from collections.abc import Iterable
@@ -60,7 +62,7 @@ def render(paths: Iterable[str], install: Iterable[str] = ()) -> str:
     return (2 * os.linesep).join(contents)
 
 
-def _render_install_block(install: Iterable[str]):
+def _render_install_block(install: Iterable[str]) -> str:
     install_sources = defaultdict(list)
     for root, fname in (os.path.split(src) for src in install):
         install_sources[root].append(fname)
diff --git a/babelizer/_files/readme.py b/babelizer/_files/readme.py
index 9308fd0..f9cdbf9 100644
--- a/babelizer/_files/readme.py
+++ b/babelizer/_files/readme.py
@@ -1,10 +1,14 @@
+from __future__ import annotations
+
+from typing import Any
+
 from jinja2 import Environment
 from jinja2 import FileSystemLoader
 
 from babelizer._datadir import get_datadir
 
 
-def render(context):
+def render(context: dict[str, Any]) -> str:
     env = Environment(loader=FileSystemLoader(get_datadir()))
     template = env.get_template("{{cookiecutter.package_name}}/README.rst")
 
diff --git a/babelizer/cli.py b/babelizer/cli.py
index be19859..42b49ac 100644
--- a/babelizer/cli.py
+++ b/babelizer/cli.py
@@ -1,10 +1,15 @@
 """The command line interface to the babelizer."""
 
+from __future__ import annotations
+
 import fnmatch
+import io
 import os
 import pathlib
 import tempfile
+from collections.abc import Collection
 from functools import partial
+from typing import cast
 
 import click
 import git
@@ -30,8 +35,8 @@
 class BabelizerAbort(click.Abort):
     """Exception raised when a user interrupts the babelizer."""
 
-    def __init__(self, message):
-        err(str(message))
+    def __init__(self, message: str):
+        err(message)
 
 
 @click.group()
@@ -42,7 +47,7 @@ def __init__(self, message):
     type=click.Path(exists=True, file_okay=False, dir_okay=True, readable=True),
     help="Change to directory, then execute.",
 )
-def babelize(cd):
+def babelize(cd: str) -> None:
     """Wrap BMI libraries with Python bindings."""
     os.chdir(cd)
 
@@ -71,12 +76,14 @@ def babelize(cd):
     help="The initial version of the babelized package",
 )
 @click.argument("meta", type=click.File(mode="r"))
-def init(meta, template, quiet, verbose, package_version):
+def init(
+    meta: click.File, template: str, quiet: bool, verbose: bool, package_version: str
+) -> None:
     """Initialize a repository with babelized project files.
 
     META is babelizer configuration information, usually saved to a file.
     """
-    output = pathlib.Path(".")
+    output = "."
     template = template or get_datadir()
 
     if not quiet:
@@ -84,9 +91,9 @@ def init(meta, template, quiet, verbose, package_version):
 
     fmt = pathlib.Path(meta.name).suffix[1:] or "toml"
     try:
-        babel_metadata = BabelMetadata.from_stream(meta, fmt=fmt)
+        babel_metadata = BabelMetadata.from_stream(cast(io.TextIOBase, meta), fmt=fmt)
     except (ScanError, ValidationError) as error:
-        raise BabelizerAbort(error)
+        raise BabelizerAbort(str(error))
 
     try:
         new_folder = render(
@@ -97,13 +104,12 @@ def init(meta, template, quiet, verbose, package_version):
             version=package_version,
         )
     except (ValidationError, OutputDirExistsError) as error:
-        raise BabelizerAbort(error)
+        raise BabelizerAbort(str(error))
 
     if not quiet:
         out(
-            "Don't forget to drop model metadata files into {}".format(
-                new_folder / "meta"
-            )
+            "Don't forget to drop model metadata files into"
+            f" {os.path.join(new_folder, 'meta')}"
         )
     repo = git.Repo(new_folder)
     repo.git.add("--all")
@@ -133,13 +139,17 @@ def init(meta, template, quiet, verbose, package_version):
 @click.option(
     "--set-version", default=None, help="Set the version of the updated package"
 )
-def update(template, quiet, verbose, set_version):
+def update(
+    template: str | None, quiet: bool, verbose: bool, set_version: str | None
+) -> None:
     """Update an existing babelized project."""
-    package_path = pathlib.Path(".").resolve()
 
+    package_path = os.path.realpath(".")
     for fname in ("babel.toml", "babel.yaml", "plugin.yaml"):
-        if (package_path / fname).is_file():
-            metadata_path = package_path / fname
+        # if (package_path / fname).is_file():
+        #     metadata_path = package_path / fname
+        if os.path.isfile(os.path.join(package_path, fname)):
+            metadata_path = os.path.join(package_path, fname)
             break
     else:
         metadata_path = None
@@ -156,7 +166,7 @@ def update(template, quiet, verbose, set_version):
     try:
         babel_metadata = BabelMetadata.from_path(metadata_path)
     except ValidationError as error:
-        raise BabelizerAbort(error)
+        raise BabelizerAbort(str(error))
 
     try:
         version = set_version or get_setup_py_version()
@@ -170,12 +180,14 @@ def update(template, quiet, verbose, set_version):
                 ]
             )
         )
+    version = "0.1.0" if version is None else version
 
     out(f"re-rendering {package_path}")
     with save_files(["CHANGES.rst", "CREDITS.rst"]):
         render(
             babel_metadata,
-            package_path.parent,
+            os.path.dirname(package_path),
+            # package_path.parent,
             template=template,
             clobber=True,
             version=version,
@@ -196,22 +208,21 @@ def update(template, quiet, verbose, set_version):
 
     if not quiet:
         out(
-            "Don't forget to drop model metadata files into {}".format(
-                package_path / "meta"
-            )
+            "Don't forget to drop model metadata files into"
+            f" {os.path.join(package_path, 'meta')}"
         )
 
     print(package_path)
 
 
 @babelize.command()
-def sample_config():
+def sample_config() -> None:
     """Generate the babelizer configuration file."""
     print_sample_config()
 
 
 @babelize.command()
-def sample_license():
+def sample_license() -> None:
     """Generate a license file."""
     context = {
         "info": {
@@ -224,7 +235,7 @@ def sample_license():
 
 
 @babelize.command()
-def sample_gitignore():
+def sample_gitignore() -> None:
     """Generate a .gitignore file."""
     context = {
         "package": {"name": "springfield_monorail"},
@@ -235,7 +246,7 @@ def sample_gitignore():
 
 @babelize.command()
 @click.argument("extension", nargs=-1)
-def sample_meson_build(extension):
+def sample_meson_build(extension: Collection[str]) -> None:
     """Generate a meson.build file."""
     if len(extension) == 0:
         contents = render_meson_build(
@@ -259,7 +270,7 @@ def sample_meson_build(extension):
 
 
 @babelize.command()
-def sample_readme():
+def sample_readme() -> None:
     context = {
         "cookiecutter": {
             "language": "python",
@@ -280,26 +291,27 @@ def sample_readme():
     print(render_readme(context))
 
 
-def _get_dir_contents(base, trunk=None):
-    base = pathlib.Path(base)
+def _get_dir_contents(base: str, trunk: str | None = None) -> set[str]:
     files = set()
-    for item in base.iterdir():
-        if item.is_dir():
+    for item in os.listdir(base):
+        if os.path.isdir(item):
             files |= _get_dir_contents(item, trunk=trunk)
         else:
-            files.add(str(item.relative_to(trunk)))
+            files.add(os.path.relpath(item, start=trunk))
 
     return files
 
 
-def _repo_contents(base):
-    repo = git.Repo(str(base))
+def _repo_contents(base: str) -> set[str]:
+    repo = git.Repo(base)
     return set(
         repo.git.ls_tree("--full-tree", "-r", "--name-only", "HEAD").splitlines()
     )
 
 
-def _generated_files(babel_metadata, template=None, version="0.1"):
+def _generated_files(
+    babel_metadata: BabelMetadata, template: str | None = None, version: str = "0.1"
+) -> set[str]:
     with tempfile.TemporaryDirectory() as tmpdir:
         new_folder = render(
             babel_metadata,
diff --git a/babelizer/metadata.py b/babelizer/metadata.py
index c98260c..c407cae 100644
--- a/babelizer/metadata.py
+++ b/babelizer/metadata.py
@@ -1,12 +1,18 @@
 """Library metadata used by the babelizer to wrap libraries."""
 
+from __future__ import annotations
+
+import io
 import pathlib
 import sys
 import warnings
 from collections import defaultdict
+from collections.abc import Callable
 from collections.abc import Generator
+from collections.abc import Iterable
 from collections.abc import Mapping
 from contextlib import suppress
+from typing import Any
 
 import tomli_w
 import yaml
@@ -20,7 +26,11 @@
 from babelizer.errors import ValidationError
 
 
-def validate_dict(meta, required=None, optional=None):
+def validate_dict(
+    meta: dict[str, Any],
+    required: Iterable[str] | None = None,
+    optional: Iterable[str] | None = None,
+) -> None:
     """Validate babelizer configuration metadata.
 
     Parameters
@@ -57,7 +67,7 @@ def validate_dict(meta, required=None, optional=None):
         )
 
 
-def _norm_os(name):
+def _norm_os(name: str) -> str:
     if name == "linux":
         name = "ubuntu"
     elif name == "mac":
@@ -67,13 +77,22 @@ def _norm_os(name):
     return name
 
 
-class BabelMetadata(Mapping):
+class BabelMetadata(Mapping[str, Any]):
     """Library metadata."""
 
-    LOADERS = {"yaml": yaml.safe_load, "toml": tomllib.loads}
+    LOADERS: dict[str, Callable[[str], dict[str, Any]]] = {
+        "yaml": yaml.safe_load,
+        "toml": tomllib.loads,
+    }
 
     def __init__(
-        self, library=None, build=None, package=None, info=None, plugin=None, ci=None
+        self,
+        library: dict[str, Any] | None = None,
+        build: dict[str, Any] | None = None,
+        package: dict[str, Any] | None = None,
+        info: dict[str, Any] | None = None,
+        plugin: dict[str, Any] | None = None,
+        ci: dict[str, Any] | None = None,
     ):
         """Metadata used by the babelizer to wrap a library.
 
@@ -122,7 +141,7 @@ def __len__(self) -> int:
         return len(self._meta)
 
     @classmethod
-    def from_stream(cls, stream, fmt="toml"):
+    def from_stream(cls, stream: io.TextIOBase, fmt: str = "toml") -> BabelMetadata:
         """Create an instance of BabelMetadata from a file-like object.
 
         Parameters
@@ -154,7 +173,7 @@ def from_stream(cls, stream, fmt="toml"):
         return cls(**meta)
 
     @classmethod
-    def from_path(cls, filepath):
+    def from_path(cls, filepath: str) -> BabelMetadata:
         """Create an instance of BabelMetadata from a path-like object.
 
         Parameters
@@ -171,25 +190,8 @@ def from_path(cls, filepath):
         with open(filepath) as fp:
             return BabelMetadata.from_stream(fp, fmt=path.suffix[1:])
 
-    def get(self, section, value):
-        """Get a metadata value from the given section.
-
-        Parameters
-        ----------
-        section : str
-            Section name.
-        value : str
-            Key name.
-
-        Returns
-        -------
-        value
-            Metadata value.
-        """
-        return self._meta[section][value]
-
     @staticmethod
-    def validate(config):
+    def validate(config: dict[str, Any]) -> None:
         """Ensure babelizer configuration metadata are valid.
 
         Parameters
@@ -262,8 +264,8 @@ def validate(config):
             )
 
     @staticmethod
-    def _handle_old_style_entry_points(library):
-        def _header_ext(language):
+    def _handle_old_style_entry_points(library: dict[str, Any]) -> dict[str, Any]:
+        def _header_ext(language: str) -> str:
             try:
                 return {"c": ".h", "c++": ".hxx"}[language]
             except KeyError:
@@ -275,20 +277,20 @@ def _header_ext(language):
 
         libraries = {}
         for entry_point in entry_points:
-            babelized_class, library, class_name = BabelMetadata.parse_entry_point(
+            babelized_class, library_name, class_name = BabelMetadata.parse_entry_point(
                 entry_point
             )
             libraries[babelized_class] = {
                 "language": language,
-                "library": library,
-                "header": library + _header_ext(language),
+                "library": library_name,
+                "header": library_name + _header_ext(language),
                 "entry_point": class_name,
             }
 
         return libraries
 
     @staticmethod
-    def _handle_old_style_info(info):
+    def _handle_old_style_info(info: dict[str, Any]) -> dict[str, Any]:
         return {
             "package_author": info["plugin_author"],
             "package_author_email": info["plugin_author_email"],
@@ -298,7 +300,7 @@ def _handle_old_style_info(info):
         }
 
     @staticmethod
-    def norm(config):
+    def norm(config: dict[str, Any]) -> dict[str, Any]:
         """Ensure current style metadata are used in babelizer configuration.
 
         Parameters
@@ -311,7 +313,7 @@ def norm(config):
         dict
             A dict of babelizer configuration metadata.
         """
-        build = defaultdict(list)
+        build: dict[str, list[str]] = defaultdict(list)
         with suppress(KeyError):
             build.update(config["build"])
 
@@ -349,7 +351,7 @@ def norm(config):
             },
         }
 
-    def dump(self, fp, fmt="toml"):
+    def dump(self, fp: io.TextIOBase, fmt: str = "toml") -> None:
         """Write serialized metadata to a file.
 
         Parameters
@@ -361,7 +363,7 @@ def dump(self, fp, fmt="toml"):
         """
         print(self.format(fmt=fmt), file=fp, end="")
 
-    def format(self, fmt="toml"):
+    def format(self, fmt: str = "toml") -> str:
         """Serialize metadata to output format.
 
         Parameters
@@ -376,7 +378,7 @@ def format(self, fmt="toml"):
         """
         return getattr(self, f"format_{fmt}")()
 
-    def format_toml(self):
+    def format_toml(self) -> str:
         """Serialize metadata as TOML.
 
         Returns
@@ -387,7 +389,7 @@ def format_toml(self):
         return tomli_w.dumps(self._meta, multiline_strings=True)
 
     @staticmethod
-    def parse_entry_point(specifier):
+    def parse_entry_point(specifier: str) -> tuple[str, str, str]:
         """Parse an entry point specifier into its parts.
 
         Parameters
@@ -413,7 +415,7 @@ def parse_entry_point(specifier):
 
         >>> BabelMetadata.parse_entry_point("bar:Baz")
         Traceback (most recent call last):
-        ,,,
+        ...
         babelizer.errors.ValidationError: bad entry point specifier (bar:Baz). specifier must be of the form name=module:class
         """
         try:
@@ -426,7 +428,7 @@ def parse_entry_point(specifier):
 
         return name, module, obj
 
-    def as_cookiecutter_context(self):
+    def as_cookiecutter_context(self) -> dict[str, Any]:
         """Format metadata in cookiecutter context.
 
         Returns
diff --git a/babelizer/render.py b/babelizer/render.py
index 48ccb17..bd2e8d5 100644
--- a/babelizer/render.py
+++ b/babelizer/render.py
@@ -1,14 +1,19 @@
 """Render a new babelized project."""
 
+from __future__ import annotations
+
 import contextlib
 import os
-import pathlib
 import sys
+from collections.abc import Generator
+from typing import Any
 
 import git
 from cookiecutter.exceptions import OutputDirExistsException
 from cookiecutter.main import cookiecutter
 
+from babelizer.metadata import BabelMetadata
+
 try:
     import black as blk
     import isort
@@ -21,11 +26,8 @@
     import tomllib
 else:  # pragma: no cover (<PY311)
     import tomli as tomllib
-if sys.version_info >= (3, 12):  # pragma: no cover (PY12+)
-    import importlib.resources as importlib_resources
-else:  # pragma: no cover (<PY312)
-    import importlib_resources
 
+from babelizer._datadir import get_datadir
 from babelizer._files.bmi_py import render as render_bmi
 from babelizer._files.gitignore import render as render_gitignore
 from babelizer._files.init_py import render as render_init
@@ -36,13 +38,13 @@
 
 
 def render(
-    plugin_metadata,
-    output,
-    template=None,
-    clobber=False,
-    version="0.1",
-    make_pretty=False,
-):
+    plugin_metadata: BabelMetadata,
+    output: str,
+    template: str | None = None,
+    clobber: bool = False,
+    version: str = "0.1",
+    make_pretty: bool = False,
+) -> str:
     """Generate a babelized library.
 
     Parameters
@@ -71,7 +73,7 @@ def render(
         Raised if output directory exists and clobber is not set.
     """
     if template is None:
-        template = str(importlib_resources.files("babelizer") / "data")
+        template = get_datadir()
 
     context = plugin_metadata.as_cookiecutter_context()
     context["files"] = {
@@ -92,16 +94,21 @@ def render(
     except OutputDirExistsException as err:
         raise OutputDirExistsError(", ".join(err.args))
 
-    with open(path / "babel.toml", "w") as fp:
+    with open(os.path.join(path, "babel.toml"), "w") as fp:
         plugin_metadata.dump(fp, fmt="toml")
 
     if make_pretty and MAKE_PRETTY:
         prettify_python(path)
 
-    return path.resolve()
+    return os.path.realpath(path)
 
 
-def render_plugin_repo(template, context=None, output_dir=".", clobber=False):
+def render_plugin_repo(
+    template: str,
+    context: dict[str, Any] | None = None,
+    output_dir: str = ".",
+    clobber: bool = False,
+) -> str:
     """Render a repository for a pymt plugin.
 
     Parameters
@@ -120,7 +127,6 @@ def render_plugin_repo(template, context=None, output_dir=".", clobber=False):
     path
         Absolute path to the newly-created repository.
     """
-    output_dir = pathlib.Path(output_dir)
     context = context or {}
 
     try:
@@ -138,8 +144,8 @@ def render_plugin_repo(template, context=None, output_dir=".", clobber=False):
 
     # path = os.path.join(output_dir, "{}".format(context["package_name"]))
     # if not os.path.isdir(path):
-    path = output_dir / f"{name}"
-    if not path.is_dir():
+    path = os.path.join(output_dir, name)
+    if not os.path.isdir(path):
         raise RenderError(f"error creating {path}")
 
     git.Repo.init(path)
@@ -148,7 +154,7 @@ def render_plugin_repo(template, context=None, output_dir=".", clobber=False):
 
 
 @contextlib.contextmanager
-def as_cwd(path):
+def as_cwd(path: str) -> Generator[None, None, None]:
     """Change directory context.
 
     Parameters
@@ -162,7 +168,7 @@ def as_cwd(path):
     os.chdir(prev_cwd)
 
 
-def blacken_file(filepath):
+def blacken_file(filepath: str) -> None:
     """Format a Python file with ``black``.
 
     Parameters
@@ -182,7 +188,7 @@ def blacken_file(filepath):
             fp.write(new_contents)
 
 
-def prettify_python(path_to_repo):
+def prettify_python(path_to_repo: str) -> None:
     """Format files in babelized project with ``black``.
 
     Parameters
@@ -190,15 +196,14 @@ def prettify_python(path_to_repo):
     path_to_repo : str
         Path-like object to babelized project.
     """
-    path_to_repo = pathlib.Path(path_to_repo)
-    with open(path_to_repo / "babel.toml") as fp:
+    with open(os.path.join(path_to_repo, "babel.toml")) as fp:
         meta = tomllib.loads(fp.read())
     module_name = meta["package"]["name"]
 
     files_to_fix = [
-        path_to_repo / module_name / "_bmi.py",
-        path_to_repo / module_name / "__init__.py",
-        path_to_repo / "docs" / "conf.py",
+        os.path.join(path_to_repo, module_name, "_bmi.py"),
+        os.path.join(path_to_repo, module_name, "__init__.py"),
+        os.path.join(path_to_repo, "docs", "conf.py"),
     ]
 
     config = isort.Config(quiet=True)
diff --git a/babelizer/utils.py b/babelizer/utils.py
index eaa6dc4..887c038 100644
--- a/babelizer/utils.py
+++ b/babelizer/utils.py
@@ -5,14 +5,16 @@
 import pathlib
 import subprocess
 import sys
-from collections.abc import Iterator
+from collections.abc import Generator
+from collections.abc import Iterable
+from collections.abc import Sequence
 from contextlib import contextmanager
 from contextlib import suppress
 
 from babelizer.errors import SetupPyError
 
 
-def execute(args):
+def execute(args: Sequence[str]) -> subprocess.CompletedProcess[bytes]:
     """Run a command through the ``subprocess`` module.
 
     Parameters
@@ -28,7 +30,7 @@ def execute(args):
     return subprocess.run(args, capture_output=True, check=True)
 
 
-def setup_py(*args):
+def setup_py(*args: str) -> list[str]:
     """Format the command to build/install the babelized package.
 
     Returns
@@ -67,7 +69,7 @@ def get_setup_py_version() -> str | None:
 
 
 @contextmanager
-def save_files(files: Iterator[str]):
+def save_files(files: Iterable[str]) -> Generator[dict[str, str], None, None]:
     """Generate repository files through a context.
 
     Parameters
diff --git a/news/94.misc b/news/94.misc
new file mode 100644
index 0000000..2624de8
--- /dev/null
+++ b/news/94.misc
@@ -0,0 +1,2 @@
+
+Added type annotations to the *babelizer*.
diff --git a/pyproject.toml b/pyproject.toml
index 2ff094e..47a72c4 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -148,6 +148,14 @@ skip = [
     "babelizer/data",
 ]
 
+[tool.mypy]
+check_untyped_defs = true
+disallow_any_generics = true
+disallow_incomplete_defs = true
+disallow_untyped_defs = true
+warn_redundant_casts = true
+warn_unused_ignores = true
+
 [tool.pytest.ini_options]
 minversion = "6.0"
 testpaths = [