diff --git a/src/ducktools/pythonfinder/__init__.py b/src/ducktools/pythonfinder/__init__.py
index 9001866..c2d2caf 100644
--- a/src/ducktools/pythonfinder/__init__.py
+++ b/src/ducktools/pythonfinder/__init__.py
@@ -43,7 +43,7 @@
     from .linux import get_python_installs
 
 
-def list_python_installs(*, finder: DetailFinder | None = None):
+def list_python_installs(*, finder: DetailFinder | None = None) -> list[PythonInstall]:
     finder = DetailFinder() if finder is None else finder
     return sorted(
         get_python_installs(finder=finder),
diff --git a/src/ducktools/pythonfinder/__main__.py b/src/ducktools/pythonfinder/__main__.py
index 93ee1ca..5d9d782 100644
--- a/src/ducktools/pythonfinder/__main__.py
+++ b/src/ducktools/pythonfinder/__main__.py
@@ -27,8 +27,15 @@
 import os
 
 from ducktools.lazyimporter import LazyImporter, ModuleImport, FromImport
-from ducktools.pythonfinder import list_python_installs, __version__
-from ducktools.pythonfinder.shared import purge_caches
+
+from . import list_python_installs, __version__
+from .shared import purge_caches
+
+
+TYPE_CHECKING = False
+if TYPE_CHECKING:
+    import argparse
+
 
 _laz = LazyImporter(
     [
@@ -49,7 +56,7 @@ class UnsupportedPythonError(Exception):
     pass
 
 
-def stop_autoclose():
+def stop_autoclose() -> None:
     """
     Checks if it thinks windows will auto close the window after running
 
@@ -76,11 +83,11 @@ def stop_autoclose():
         _laz.subprocess.run("pause", shell=True)
 
 
-def _get_parser_class():
+def _get_parser_class() -> type[argparse.ArgumentParser]:
     # This class is deferred to avoid the argparse import
     # if there are no arguments to parse
 
-    class FixedArgumentParser(_laz.argparse.ArgumentParser):
+    class FixedArgumentParser(_laz.argparse.ArgumentParser):  # type: ignore
         """
         The builtin argument parser uses shutil to figure out the terminal width
         to display help info. This one replaces the function that calls help info
@@ -108,7 +115,7 @@ def _get_formatter(self):
     return FixedArgumentParser
 
 
-def get_parser():
+def get_parser() -> argparse.ArgumentParser:
     FixedArgumentParser = _get_parser_class()  # noqa
 
     parser = FixedArgumentParser(
@@ -162,16 +169,16 @@ def get_parser():
 
 
 def display_local_installs(
-    min_ver=None,
-    max_ver=None,
-    compatible=None,
-):
+    min_ver: str | None = None,
+    max_ver: str | None = None,
+    compatible: str | None = None,
+) -> None:
     if min_ver:
-        min_ver = tuple(int(i) for i in min_ver.split("."))
+        min_ver_tuple = tuple(int(i) for i in min_ver.split("."))
     if max_ver:
-        max_ver = tuple(int(i) for i in max_ver.split("."))
+        max_ver_tuple = tuple(int(i) for i in max_ver.split("."))
     if compatible:
-        compatible = tuple(int(i) for i in compatible.split("."))
+        compatible_tuple = tuple(int(i) for i in compatible.split("."))
 
     installs = list_python_installs()
 
@@ -185,15 +192,15 @@ def display_local_installs(
 
     # First collect the strings
     for install in installs:
-        if min_ver and install.version < min_ver:
+        if min_ver and install.version < min_ver_tuple:
             continue
-        elif max_ver and install.version > max_ver:
+        elif max_ver and install.version > max_ver_tuple:
             continue
         elif compatible:
-            if install.version < compatible:
+            if install.version < compatible_tuple:
                 continue
             version_parts = len(compatible) - 1
-            if install.version[:version_parts] > compatible[:-1]:
+            if install.version[:version_parts] > compatible_tuple[:-1]:
                 continue
 
         version_str = install.version_str
@@ -253,14 +260,14 @@ def display_local_installs(
 
 
 def display_remote_binaries(
-    min_ver,
-    max_ver,
-    compatible,
-    all_binaries,
-    system,
-    machine,
-    prerelease
-):
+    min_ver: str,
+    max_ver: str,
+    compatible: str,
+    all_binaries: bool,
+    system: str,
+    machine: str,
+    prerelease: bool,
+) -> None:
     specs = []
     if min_ver:
         specs.append(f">={min_ver}")
@@ -294,7 +301,7 @@ def display_remote_binaries(
         print("No Python releases found matching specification")
 
 
-def main():
+def main() -> int:
     if sys.version_info < (3, 8):
         v = sys.version_info
         raise UnsupportedPythonError(
@@ -334,7 +341,9 @@ def main():
         display_local_installs()
 
     stop_autoclose()
+    
+    return 0
 
 
 if __name__ == "__main__":
-    main()
+    sys.exit(main())
diff --git a/src/ducktools/pythonfinder/linux/pyenv_search.py b/src/ducktools/pythonfinder/linux/pyenv_search.py
index ebe5374..026c464 100644
--- a/src/ducktools/pythonfinder/linux/pyenv_search.py
+++ b/src/ducktools/pythonfinder/linux/pyenv_search.py
@@ -74,7 +74,7 @@ def get_pyenv_root() -> str | None:
 def get_pyenv_pythons(
     versions_folder: str | os.PathLike | None = None,
     *,
-    finder: DetailFinder = None,
+    finder: DetailFinder | None = None,
 ) -> Iterator[PythonInstall]:
     if versions_folder is None:
         if pyenv_root := get_pyenv_root():
@@ -90,7 +90,7 @@ def get_pyenv_pythons(
     finder = DetailFinder() if finder is None else finder
 
     with finder:
-        for p in sorted(os.scandir(versions_folder), key=lambda x: x.path):
+        for p in sorted(os.scandir(str(versions_folder)), key=lambda x: x.path):
             # Don't include folders that are venvs
             venv_indicator = os.path.join(p.path, "pyvenv.cfg")
             if os.path.exists(venv_indicator):
diff --git a/src/ducktools/pythonfinder/py.typed b/src/ducktools/pythonfinder/py.typed
new file mode 100644
index 0000000..b648ac9
--- /dev/null
+++ b/src/ducktools/pythonfinder/py.typed
@@ -0,0 +1 @@
+partial
diff --git a/src/ducktools/pythonfinder/pythonorg_search.py b/src/ducktools/pythonfinder/pythonorg_search.py
index 19eb9ec..dae35e2 100644
--- a/src/ducktools/pythonfinder/pythonorg_search.py
+++ b/src/ducktools/pythonfinder/pythonorg_search.py
@@ -39,7 +39,8 @@
 from packaging.version import Version
 
 from ducktools.classbuilder.prefab import Prefab, attribute, get_attributes
-from ducktools.pythonfinder.shared import version_str_to_tuple
+
+from .shared import version_str_to_tuple
 
 
 RELEASE_PAGE = "https://www.python.org/api/v2/downloads/release/"
@@ -341,6 +342,7 @@ def latest_binary_match(self, specifier: SpecifierSet, prereleases=False) -> Pyt
             for download in self.matching_downloads(specifier, prereleases):
                 if download.url.endswith(tag):
                     return download
+        return None
 
     def latest_python_download(self, prereleases=False) -> PythonDownload | None:
         """
@@ -369,3 +371,4 @@ def latest_python_download(self, prereleases=False) -> PythonDownload | None:
                                 md5_sum=release_file.md5_sum,
                             )
                             return download
+        return None
\ No newline at end of file
diff --git a/src/ducktools/pythonfinder/shared.py b/src/ducktools/pythonfinder/shared.py
index 168c94d..d33d712 100644
--- a/src/ducktools/pythonfinder/shared.py
+++ b/src/ducktools/pythonfinder/shared.py
@@ -190,7 +190,7 @@ def __exit__(self, exc_type, exc_val, exc_tb):
             self.save()
 
     @property
-    def raw_cache(self):
+    def raw_cache(self) -> dict:
         if self._raw_cache is None:
             try:
                 with open(self.cache_path) as f:
@@ -199,14 +199,14 @@ def raw_cache(self):
                 self._raw_cache = {}
         return self._raw_cache
 
-    def save(self):
+    def save(self) -> None:
         os.makedirs(os.path.dirname(self.cache_path), exist_ok=True)
         with open(self.cache_path, 'w') as f:
             _laz.json.dump(self.raw_cache, f, indent=4)
 
         self._dirty_cache = False
 
-    def clear_invalid_runtimes(self):
+    def clear_invalid_runtimes(self) -> None:
         """
         Remove cache entries where the python.exe no longer exists
         """
@@ -218,7 +218,7 @@ def clear_invalid_runtimes(self):
         if removed_runtimes:
             self._dirty_cache = True
 
-    def clear_cache(self):
+    def clear_cache(self) -> None:
         """
         Completely empty the cache
         """
@@ -357,6 +357,8 @@ def implementation_version(self) -> tuple[int, int, int, str, int] | None:
     def implementation_version_str(self) -> str:
         return version_tuple_to_str(self.implementation_version)
 
+    # Typing these classmethods would require an import
+    # This is not acceptable for performance reasons
     @classmethod
     def from_str(
         cls,
@@ -387,13 +389,13 @@ def from_str(
     @classmethod
     def from_json(
         cls,
-        version,
-        executable,
-        architecture,
-        implementation,
-        metadata,
-        paths=None,
-        managed_by=None,
+        version: str,
+        executable: str,
+        architecture: str,
+        implementation: str,
+        metadata: dict,
+        paths: dict | None = None,
+        managed_by: str | None = None,
     ):
         if arch_ver := metadata.get(f"{implementation}_version"):
             metadata[f"{implementation}_version"] = tuple(arch_ver)
@@ -431,6 +433,7 @@ def get_pip_version(self) -> str | None:
         return pip_call.stdout
 
 
+# Return type missing due to import requirements
 def _python_exe_regex(basename: str = "python"):
     if sys.platform == "win32":
         return _laz.re.compile(rf"{basename}\d?\.?\d*\.exe")
@@ -443,7 +446,7 @@ def get_folder_pythons(
     basenames: tuple[str, ...] = ("python", "pypy", "micropython"),
     finder: DetailFinder | None = None,
     managed_by: str | None = None,
-):
+) -> Iterator[PythonInstall]:
     regexes = [_python_exe_regex(name) for name in basenames]
 
     finder = DetailFinder() if finder is None else finder
diff --git a/src/ducktools/pythonfinder/venv.py b/src/ducktools/pythonfinder/venv.py
index bdde2b2..dcc8827 100644
--- a/src/ducktools/pythonfinder/venv.py
+++ b/src/ducktools/pythonfinder/venv.py
@@ -84,7 +84,7 @@ def version_str(self) -> str:
         return version_tuple_to_str(self.version)
 
     @property
-    def parent_executable(self) -> str:
+    def parent_executable(self) -> str | None:
         if self._parent_executable is None:
             # Guess the parent executable file
             parent_exe = None
@@ -122,7 +122,9 @@ def parent_executable(self) -> str:
 
     @property
     def parent_exists(self) -> bool:
-        return os.path.exists(self.parent_executable)
+        if self.parent_executable and os.path.exists(self.parent_executable):
+            return True
+        return False
 
     def get_parent_install(
         self,
@@ -135,6 +137,9 @@ def get_parent_install(
         finder = DetailFinder() if finder is None else finder
 
         if self.parent_exists:
+            # parent_exists forces this check
+            assert self.parent_executable is not None
+
             exe = self.parent_executable
 
             # Python installs may be cached, can skip querying exe.
@@ -253,6 +258,7 @@ def get_python_venvs(
     :param search_parent_folders: Also search parent folders
     :yield: PythonVEnv details.
     """
+    # This converts base_dir to a Path, but mypy doesn't know that
     base_dir = _laz.Path.cwd() if base_dir is None else _laz.Path(base_dir)
 
     cwd_pattern = pattern = f"*/{VENV_CONFIG_NAME}"
@@ -261,7 +267,7 @@ def get_python_venvs(
         # Only search cwd recursively, parents are searched non-recursively
         cwd_pattern = "*" + pattern
 
-    for conf in base_dir.glob(cwd_pattern):
+    for conf in base_dir.glob(cwd_pattern):  # type: ignore
         try:
             env = PythonVEnv.from_cfg(conf)
         except InvalidVEnvError:
@@ -270,7 +276,7 @@ def get_python_venvs(
 
     if search_parent_folders:
         # Search parent folders
-        for fld in base_dir.parents:
+        for fld in base_dir.parents:  # type: ignore
             try:
                 for conf in fld.glob(pattern):
                     try:
diff --git a/src/ducktools/pythonfinder/win32/pyenv_search.py b/src/ducktools/pythonfinder/win32/pyenv_search.py
index 9805349..4ef91e0 100644
--- a/src/ducktools/pythonfinder/win32/pyenv_search.py
+++ b/src/ducktools/pythonfinder/win32/pyenv_search.py
@@ -52,7 +52,7 @@ def get_pyenv_pythons(
     finder = DetailFinder() if finder is None else finder
 
     with finder:
-        for p in os.scandir(versions_folder):
+        for p in os.scandir(str(versions_folder)):
             # On windows, venv folders usually have the python.exe in \Scripts\
             # while runtimes have it in the base folder so venvs shouldn't be disovered
             # but exclude them early anyway