diff --git a/pygit2/_build.py b/pygit2/_build.py
index 4232605b..da4c34b2 100644
--- a/pygit2/_build.py
+++ b/pygit2/_build.py
@@ -40,7 +40,7 @@
 #
 # Utility functions to get the paths required for building extensions
 #
-def _get_libgit2_path():
+def _get_libgit2_path() -> Path:
     # LIBGIT2 environment variable takes precedence
     libgit2_path = os.getenv('LIBGIT2')
     if libgit2_path is not None:
@@ -52,7 +52,7 @@ def _get_libgit2_path():
     return Path('/usr/local')
 
 
-def get_libgit2_paths():
+def get_libgit2_paths() -> tuple[Path, dict[str, list[str]]]:
     # Base path
     path = _get_libgit2_path()
 
@@ -61,7 +61,7 @@ def get_libgit2_paths():
     if libgit2_lib is None:
         library_dirs = [path / 'lib', path / 'lib64']
     else:
-        library_dirs = [libgit2_lib]
+        library_dirs = [Path(libgit2_lib)]
 
     include_dirs = [path / 'include']
     return (
diff --git a/pygit2/blob.py b/pygit2/blob.py
index 1232fb2f..1ee6a9eb 100644
--- a/pygit2/blob.py
+++ b/pygit2/blob.py
@@ -84,7 +84,7 @@ def readinto(self, b, /):
         except KeyboardInterrupt:
             return 0
 
-    def close(self):
+    def close(self) -> None:
         try:
             self._ready.wait()
             self._writer_closed.wait()
diff --git a/pygit2/errors.py b/pygit2/errors.py
index 72a4af39..3ddf71eb 100644
--- a/pygit2/errors.py
+++ b/pygit2/errors.py
@@ -32,7 +32,7 @@
 value_errors = set([C.GIT_EEXISTS, C.GIT_EINVALIDSPEC, C.GIT_EAMBIGUOUS])
 
 
-def check_error(err, io=False):
+def check_error(err, io: bool = False) -> None:
     if err >= 0:
         return
 
@@ -69,5 +69,5 @@ def check_error(err, io=False):
 
 # Indicate that we want libgit2 to pretend a function was not set
 class Passthrough(Exception):
-    def __init__(self):
+    def __init__(self) -> None:
         super().__init__('The function asked for pass-through')
diff --git a/pygit2/refspec.py b/pygit2/refspec.py
index cb900e75..794e8d13 100644
--- a/pygit2/refspec.py
+++ b/pygit2/refspec.py
@@ -34,7 +34,7 @@
 class Refspec:
     """The constructor is for internal use only."""
 
-    def __init__(self, owner, ptr):
+    def __init__(self, owner, ptr) -> None:
         self._owner = owner
         self._refspec = ptr
 
diff --git a/pygit2/utils.py b/pygit2/utils.py
index b3d5d141..22fde943 100644
--- a/pygit2/utils.py
+++ b/pygit2/utils.py
@@ -80,7 +80,7 @@ def to_bytes(
     return s.encode(encoding, errors)  # type: ignore[union-attr]
 
 
-def to_str(s):
+def to_str(s: str | bytes | os.PathLike[str] | os.PathLike[bytes]) -> str:
     if hasattr(s, '__fspath__'):
         s = os.fspath(s)
 
@@ -110,7 +110,7 @@ def new_git_strarray() -> Generator['GitStrrayC', None, None]:
     C.git_strarray_dispose(strarray)
 
 
-def strarray_to_strings(arr):
+def strarray_to_strings(arr) -> list[str]:
     """
     Return a list of strings from a git_strarray pointer.
 
diff --git a/setup.py b/setup.py
index ff904fa9..2bd62f90 100644
--- a/setup.py
+++ b/setup.py
@@ -47,7 +47,7 @@
 
 
 class sdist_files_from_git(sdist):
-    def get_file_list(self):
+    def get_file_list(self) -> None:
         popen = Popen(
             ['git', 'ls-files'], stdout=PIPE, stderr=PIPE, universal_newlines=True
         )
@@ -56,7 +56,7 @@ def get_file_list(self):
             print(stderrdata)
             sys.exit()
 
-        def exclude(line):
+        def exclude(line: str) -> bool:
             for prefix in ['.', 'appveyor.yml', 'docs/', 'misc/']:
                 if line.startswith(prefix):
                     return True
@@ -97,11 +97,11 @@ def exclude(line):
 
 # On Windows, we install the git2.dll too.
 class BuildWithDLLs(build):
-    def _get_dlls(self):
+    def _get_dlls(self) -> list[tuple[Path, Path]]:
         # return a list of (FQ-in-name, relative-out-name) tuples.
         ret = []
         bld_ext = self.distribution.get_command_obj('build_ext')
-        compiler_type = bld_ext.compiler.compiler_type
+        compiler_type = bld_ext.compiler.compiler_type  # type: ignore[attr-defined]
         libgit2_dlls = []
         if compiler_type == 'msvc':
             libgit2_dlls.append('git2.dll')
@@ -121,7 +121,7 @@ def _get_dlls(self):
                 log.debug(f'(looked in {look_dirs})')
         return ret
 
-    def run(self):
+    def run(self) -> None:
         build.run(self)
         for s, d in self._get_dlls():
             self.copy_file(s, d)