diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index 75aa911..4e28eab 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -24,7 +24,10 @@ jobs:
           python-version: "3.9"
       - uses: Gr1N/setup-poetry@v4
       - run: poetry install
-      - run: poetry run mypy --py2 sysaudit/
+      - run: poetry run mypy --py2 sysaudit/ tests/
+        name: Mypy Check Python2
+      - run: poetry run mypy sysaudit/ tests/
+        name: Mypy Check Python3
   test:
     runs-on: ubuntu-latest
     strategy:
diff --git a/sysaudit/__init__.pyi b/sysaudit/__init__.pyi
index 881a3f3..cd66550 100644
--- a/sysaudit/__init__.pyi
+++ b/sysaudit/__init__.pyi
@@ -1,6 +1,6 @@
 import typing
 
-AuditHookCallable = typing.Callable[[str, typing.Tuple[typing.Any, ...]], None]
-
 def audit(event: str, *args: typing.Any) -> None: ...
-def addaudithook(AuditHookCallable) -> None: ...
+def addaudithook(
+    hook: typing.Callable[[str, typing.Tuple[typing.Any, ...]], None]
+) -> None: ...
diff --git a/sysaudit/_csysaudit.pyi b/sysaudit/_csysaudit.pyi
new file mode 100644
index 0000000..cd66550
--- /dev/null
+++ b/sysaudit/_csysaudit.pyi
@@ -0,0 +1,6 @@
+import typing
+
+def audit(event: str, *args: typing.Any) -> None: ...
+def addaudithook(
+    hook: typing.Callable[[str, typing.Tuple[typing.Any, ...]], None]
+) -> None: ...
diff --git a/tests/audit-tests.py b/tests/audit-tests.py
index 99e00f0..4358408 100644
--- a/tests/audit-tests.py
+++ b/tests/audit-tests.py
@@ -6,6 +6,7 @@ module with arguments identifying each test.
 """
 
 import contextlib
+import typing
 import sys
 
 import sysaudit
@@ -24,7 +25,7 @@ class TestHook:
         self.seen = []
         self.closed = False
 
-    def __enter__(self, *a):
+    def __enter__(self, *a):  # type: (typing.Any) -> TestHook
         sysaudit.addaudithook(self)
         return self
 
@@ -38,7 +39,9 @@ class TestHook:
     def seen_events(self):
         return [i[0] for i in self.seen]
 
-    def __call__(self, event, args):
+    def __call__(
+        self, event, args
+    ):  # type: (str, typing.Tuple[typing.Any, ...]) -> None
         if self.closed:
             return
         self.seen.append((event, args))
@@ -246,12 +249,12 @@ def test_mmap():
         assertEqual(hook.seen[0][1][:2], (-1, 8))
 
 
-def test_excepthook():
+def test_excepthook():  # type: () -> None
     def excepthook(exc_type, exc_value, exc_tb):
         if exc_type is not RuntimeError:
             sys.__excepthook__(exc_type, exc_value, exc_tb)
 
-    def hook(event, args):
+    def hook(event, args):  # type: (str, typing.Tuple[typing.Any, ...]) -> None
         if event == "sys.excepthook":
             if not isinstance(args[2], args[1]):
                 raise TypeError(
@@ -266,27 +269,27 @@ def test_excepthook():
     raise RuntimeError("fatal-error")
 
 
-def test_unraisablehook():
-    from _testcapi import write_unraisable_exc
+def test_unraisablehook():  # type: () -> None
+    from _testcapi import write_unraisable_exc  # type: ignore
 
     def unraisablehook(hookargs):
         pass
 
-    def hook(event, args):
+    def hook(event, args):  # type: (str, typing.Tuple[typing.Any, ...]) -> None
         if event == "sys.unraisablehook":
             if args[0] != unraisablehook:
                 raise ValueError("Expected {} == {}".format(args[0], unraisablehook))
             print(event, repr(args[1].exc_value), args[1].err_msg)
 
     sysaudit.addaudithook(hook)
-    sys.unraisablehook = unraisablehook
+    sys.unraisablehook = unraisablehook  # type: ignore [attr-defined]
     write_unraisable_exc(RuntimeError("nonfatal-error"), "for audit hook test", None)
 
 
-def test_winreg():
-    from winreg import OpenKey, EnumKey, CloseKey, HKEY_LOCAL_MACHINE
+def test_winreg():  # type: () -> None
+    from winreg import OpenKey, EnumKey, CloseKey, HKEY_LOCAL_MACHINE  # type: ignore
 
-    def hook(event, args):
+    def hook(event, args):  # type: (str, typing.Tuple[typing.Any, ...]) -> None
         if not event.startswith("winreg."):
             return
         print(event, args)
@@ -306,10 +309,10 @@ def test_winreg():
     CloseKey(kv)
 
 
-def test_socket():
+def test_socket():  # type: () -> None
     import socket
 
-    def hook(event, args):
+    def hook(event, args):  # type: (str, typing.Tuple[typing.Any, ...]) -> None
         if event.startswith("socket."):
             print(event, args)
 
diff --git a/tests/test_import.py b/tests/test_import.py
index 064b148..7842bf5 100644
--- a/tests/test_import.py
+++ b/tests/test_import.py
@@ -3,10 +3,10 @@ import sys
 import sysaudit
 
 
-def test_module():
+def test_module():  # type: () -> None
     if sys.version_info >= (3, 8, 0):
-        assert sysaudit.audit == sys.audit
-        assert sysaudit.addaudithook == sys.addaudithook
+        assert sysaudit.audit == sys.audit  # type: ignore [attr-defined]
+        assert sysaudit.addaudithook == sys.addaudithook  # type: ignore [attr-defined]
     else:
         assert sysaudit.audit == sysaudit._csysaudit.audit
         assert sysaudit.addaudithook == sysaudit._csysaudit.addaudithook