diff --git a/demo/model_app.py b/demo/model_app.py
index 3dffd4a..1a5eb67 100644
--- a/demo/model_app.py
+++ b/demo/model_app.py
@@ -9,7 +9,7 @@
 
 
 class MainWindow(QModelMainWindow):
-    def __init__(self, app: Application):
+    def __init__(self, app: Application) -> None:
         super().__init__(app)
 
         self._cur_file: str = ""
diff --git a/demo/multi_file/functions.py b/demo/multi_file/functions.py
index e04692d..0e83201 100644
--- a/demo/multi_file/functions.py
+++ b/demo/multi_file/functions.py
@@ -1,31 +1,31 @@
 from qtpy.QtWidgets import QApplication, QFileDialog
 
 
-def open_file():
+def open_file() -> None:
     name, _ = QFileDialog.getOpenFileName()
     print("Open file:", name)
 
 
-def close():
+def close() -> None:
     QApplication.activeWindow().close()
     print("close")
 
 
-def undo():
+def undo() -> None:
     print("undo")
 
 
-def redo():
+def redo() -> None:
     print("redo")
 
 
-def cut():
+def cut() -> None:
     print("cut")
 
 
-def copy():
+def copy() -> None:
     print("copy")
 
 
-def paste():
+def paste() -> None:
     print("paste")
diff --git a/demo/qapplication.py b/demo/qapplication.py
index 6050f8c..9989a36 100644
--- a/demo/qapplication.py
+++ b/demo/qapplication.py
@@ -17,7 +17,7 @@
 
 
 class MainWindow(QMainWindow):
-    def __init__(self):
+    def __init__(self) -> None:
         super().__init__()
 
         self._cur_file = ""
@@ -32,28 +32,28 @@ def __init__(self):
 
         self.set_current_file("")
 
-    def new_file(self):
+    def new_file(self) -> None:
         if self.maybe_save():
             self._text_edit.clear()
             self.set_current_file("")
 
-    def open(self):
+    def open(self) -> None:
         if self.maybe_save():
             fileName, filtr = QFileDialog.getOpenFileName(self)
             if fileName:
                 self.load_file(fileName)
 
-    def save(self):
+    def save(self) -> bool:
         return self.save_file(self._cur_file) if self._cur_file else self.save_as()
 
-    def save_as(self):
+    def save_as(self) -> bool:
         fileName, filtr = QFileDialog.getSaveFileName(self)
         if fileName:
             return self.save_file(fileName)
 
         return False
 
-    def about(self):
+    def about(self) -> None:
         QMessageBox.about(
             self,
             "About Application",
@@ -62,7 +62,7 @@ def about(self):
             "toolbars, and a status bar.",
         )
 
-    def create_actions(self):
+    def create_actions(self) -> None:
         self._new_act = QAction(
             fonticon.icon(FA6S.file_circle_plus),
             "&New",
@@ -145,7 +145,7 @@ def create_actions(self):
         self._text_edit.copyAvailable.connect(self._cut_act.setEnabled)
         self._text_edit.copyAvailable.connect(self._copy_act.setEnabled)
 
-    def create_menus(self):
+    def create_menus(self) -> None:
         self._file_menu = self.menuBar().addMenu("&File")
         self._file_menu.addAction(self._new_act)
         self._file_menu.addAction(self._open_act)
@@ -164,7 +164,7 @@ def create_menus(self):
         self._help_menu = self.menuBar().addMenu("&Help")
         self._help_menu.addAction(self._about_act)
 
-    def create_tool_bars(self):
+    def create_tool_bars(self) -> None:
         self._file_tool_bar = self.addToolBar("File")
         self._file_tool_bar.addAction(self._new_act)
         self._file_tool_bar.addAction(self._open_act)
@@ -175,10 +175,10 @@ def create_tool_bars(self):
         self._edit_tool_bar.addAction(self._copy_act)
         self._edit_tool_bar.addAction(self._paste_act)
 
-    def create_status_bar(self):
+    def create_status_bar(self) -> None:
         self.statusBar().showMessage("Ready")
 
-    def maybe_save(self):
+    def maybe_save(self) -> bool:
         if self._text_edit.document().isModified():
             ret = QMessageBox.warning(
                 self,
@@ -194,7 +194,7 @@ def maybe_save(self):
                 return False
         return True
 
-    def load_file(self, fileName):
+    def load_file(self, fileName: str) -> None:
         file = QFile(fileName)
         if not file.open(QFile.OpenModeFlag.ReadOnly | QFile.OpenModeFlag.Text):
             reason = file.errorString()
@@ -211,7 +211,7 @@ def load_file(self, fileName):
         self.set_current_file(fileName)
         self.statusBar().showMessage("File loaded", 2000)
 
-    def save_file(self, fileName):
+    def save_file(self, fileName: str) -> bool:
         error = None
         QApplication.setOverrideCursor(Qt.WaitCursor)
         file = QSaveFile(fileName)
@@ -234,7 +234,7 @@ def save_file(self, fileName):
         self.statusBar().showMessage("File saved", 2000)
         return True
 
-    def set_current_file(self, fileName: str):
+    def set_current_file(self, fileName: str) -> None:
         self._cur_file = fileName
         self._text_edit.document().setModified(False)
         self.setWindowModified(False)
@@ -246,7 +246,7 @@ def set_current_file(self, fileName: str):
 
         self.setWindowTitle(f"{shown_name}[*] - Application")
 
-    def stripped_name(self, fullFileName: str):
+    def stripped_name(self, fullFileName: str) -> str:
         return QFileInfo(fullFileName).fileName()
 
 
diff --git a/pyproject.toml b/pyproject.toml
index 9ea6754..94b609c 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -117,13 +117,14 @@ select = [
     "C4",   # flake8-comprehensions
     "B",    # flake8-bugbear
     "A001", # flake8-builtins
-    # "ANN",  # flake8-annotations
-    "RUF", # ruff-specific rules
-    "TC",  # flake8-type-checking
-    "TID", # flake8-tidy-imports
+    "ANN",  # flake8-annotations
+    "RUF",  # ruff-specific rules
+    "TC",   # flake8-type-checking
+    "TID",  # flake8-tidy-imports
 ]
 ignore = [
-    "D401", # First line should be in imperative mood (remove to opt in)
+    "D401",   # First line should be in imperative mood (remove to opt in)
+    "ANN401", # Disallow typing.Any
 ]
 
 [tool.ruff.lint.pyupgrade]
@@ -131,7 +132,7 @@ ignore = [
 keep-runtime-typing = true
 
 [tool.ruff.lint.per-file-ignores]
-"tests/*.py" = ["D", "E501"]
+"tests/*.py" = ["D", "E501", "ANN"]
 "demo/*" = ["D"]
 "docs/*" = ["D"]
 "src/app_model/_registries.py" = ["D10"]
diff --git a/src/app_model/backends/qt/_qaction.py b/src/app_model/backends/qt/_qaction.py
index 862ac34..fc4f37d 100644
--- a/src/app_model/backends/qt/_qaction.py
+++ b/src/app_model/backends/qt/_qaction.py
@@ -41,7 +41,7 @@ def __init__(
         command_id: str,
         app: Application | str,
         parent: QObject | None = None,
-    ):
+    ) -> None:
         super().__init__(parent)
         self._app = Application.get_or_create(app) if isinstance(app, str) else app
         self._command_id = command_id
@@ -81,7 +81,7 @@ def __init__(
         parent: QObject | None = None,
         *,
         use_short_title: bool = False,
-    ):
+    ) -> None:
         super().__init__(command_rule.id, app, parent)
         self._cmd_rule = command_rule
         if use_short_title and command_rule.short_title:
@@ -146,7 +146,7 @@ def __init__(
         menu_item: MenuItem,
         app: Application | str,
         parent: QObject | None = None,
-    ):
+    ) -> None:
         super().__init__(menu_item.command, app, parent)
         self._menu_item = menu_item
         with contextlib.suppress(NameError):
diff --git a/src/app_model/backends/qt/_qmenu.py b/src/app_model/backends/qt/_qmenu.py
index c36ddce..bfa8a64 100644
--- a/src/app_model/backends/qt/_qmenu.py
+++ b/src/app_model/backends/qt/_qmenu.py
@@ -42,7 +42,7 @@ def __init__(
         app: Application | str,
         title: str | None = None,
         parent: QWidget | None = None,
-    ):
+    ) -> None:
         QMenu.__init__(self, parent)
 
         # NOTE: code duplication with QModelToolBar, but Qt mixins and multiple
@@ -132,7 +132,7 @@ def __init__(
         submenu: SubmenuItem,
         app: Application | str,
         parent: QWidget | None = None,
-    ):
+    ) -> None:
         assert isinstance(submenu, SubmenuItem), f"Expected str, got {type(submenu)!r}"
         self._submenu = submenu
         super().__init__(
diff --git a/src/app_model/expressions/_expressions.py b/src/app_model/expressions/_expressions.py
index 7de3316..8ec825e 100644
--- a/src/app_model/expressions/_expressions.py
+++ b/src/app_model/expressions/_expressions.py
@@ -476,7 +476,7 @@ def __init__(
         op: ast.boolop,
         values: Sequence[ConstType | Expr],
         **kwargs: Unpack[_Attributes],
-    ):
+    ) -> None:
         super().__init__(op, [Expr._cast(v) for v in values], **kwargs)
 
 
diff --git a/src/app_model/types/_keys/_keybindings.py b/src/app_model/types/_keys/_keybindings.py
index c958046..bcd6fb3 100644
--- a/src/app_model/types/_keys/_keybindings.py
+++ b/src/app_model/types/_keys/_keybindings.py
@@ -188,7 +188,7 @@ class KeyBinding:
 
     parts: list[SimpleKeyBinding] = Field(..., **MIN1)  # type: ignore
 
-    def __init__(self, *, parts: list[SimpleKeyBinding]):
+    def __init__(self, *, parts: list[SimpleKeyBinding]) -> None:
         self.parts = parts
 
     def __str__(self) -> str:
diff --git a/tests/test_actions.py b/tests/test_actions.py
index 356136d..a992e42 100644
--- a/tests/test_actions.py
+++ b/tests/test_actions.py
@@ -41,14 +41,14 @@ def test_register_action_decorator(
     if mode == "decorator":
 
         @register_action(app=app, id_or_action=cmd_id, **kwargs)
-        def f1():
+        def f1() -> str:
             return "hi"
 
         assert f1() == "hi"  # decorator returns the function
 
     else:
 
-        def f2():
+        def f2() -> str:
             return "hi"
 
         if mode == "str":
@@ -99,14 +99,14 @@ def f2():
     assert not list(app.menus)
 
 
-def test_errors(simple_app: Application):
+def test_errors(simple_app: Application) -> None:
     with pytest.raises(ValueError, match="'title' is required"):
         simple_app.register_action("cmd_id")  # type: ignore
     with pytest.raises(TypeError, match="must be a string or an Action"):
         simple_app.register_action(None)  # type: ignore
 
 
-def test_register_multiple_actions(simple_app: Application):
+def test_register_multiple_actions(simple_app: Application) -> None:
     actions: list[Action] = [
         Action(id="cmd_id1", title="title1", callback=lambda: None),
         Action(id="cmd_id2", title="title2", callback=lambda: None),
diff --git a/tests/test_context/test_context.py b/tests/test_context/test_context.py
index 2a40fe3..c20f798 100644
--- a/tests/test_context/test_context.py
+++ b/tests/test_context/test_context.py
@@ -7,7 +7,7 @@
 from app_model.expressions._context import _OBJ_TO_CONTEXT
 
 
-def test_create_context():
+def test_create_context() -> None:
     """You can create a context for any object"""
 
     class T: ...
@@ -30,7 +30,7 @@ class T: ...
         create_context(T(), root={})  # type: ignore
 
 
-def test_create_and_get_scoped_contexts():
+def test_create_and_get_scoped_contexts() -> None:
     """Test that objects created in the stack of another contexted object.
 
     likely the most common way that this API will be used:
@@ -61,7 +61,7 @@ def __init__(self) -> None:
     assert len(_OBJ_TO_CONTEXT) == before
 
 
-def test_context_events():
+def test_context_events() -> None:
     """Changing context keys emits an event"""
     mock = Mock()
     root = Context()
diff --git a/tests/test_context/test_expressions.py b/tests/test_context/test_expressions.py
index 408eea1..8669e2a 100644
--- a/tests/test_context/test_expressions.py
+++ b/tests/test_context/test_expressions.py
@@ -7,7 +7,7 @@
 from app_model.expressions._expressions import _OPS, _iter_names
 
 
-def test_names():
+def test_names() -> None:
     expr = Name("n", bound=int)
     assert expr.eval({"n": 5}) == 5
 
@@ -18,7 +18,7 @@ def test_names():
     assert repr(Name("n")) == "Expr.parse('n')"
 
 
-def test_constants():
+def test_constants() -> None:
     assert Constant(1).eval() == 1
     assert Constant(3.14).eval() == 3.14
 
@@ -40,7 +40,7 @@ def test_constants():
         Constant((1, 2))  # type: ignore
 
 
-def test_bool_ops():
+def test_bool_ops() -> None:
     n1 = Name[bool]("n1")
     true = Constant(True)
     false = Constant(False)
@@ -68,7 +68,7 @@ def test_bool_ops():
     assert not isinstance(Constant(1) and 1, Expr)
 
 
-def test_bin_ops():
+def test_bin_ops() -> None:
     one = Constant(1)
     assert (one + 1).eval() == 2
     assert (one - 1).eval() == 0
@@ -86,7 +86,7 @@ def test_bin_ops():
     assert (Constant(16).bitor(4)).eval() == 20
 
 
-def test_unary_ops():
+def test_unary_ops() -> None:
     assert Constant(1).eval() == 1
     assert (+Constant(1)).eval() == 1
     assert (-Constant(1)).eval() == -1
@@ -94,7 +94,7 @@ def test_unary_ops():
     assert (~Constant(True)).eval() is False
 
 
-def test_comparison():
+def test_comparison() -> None:
     n = Name[int]("n")
     n2 = Name[int]("n2")
     one = Constant(1)
@@ -140,7 +140,7 @@ def test_comparison():
     assert repr(n > n2) == "Expr.parse('n > n2')"
 
 
-def test_iter_names():
+def test_iter_names() -> None:
     expr = "a if b in c else d > e"
     a = parse_expression(expr)
     assert a is parse_expression(a)
@@ -201,18 +201,18 @@ def test_iter_names():
 
 
 @pytest.mark.parametrize("expr", GOOD_EXPRESSIONS)
-def test_serdes(expr):
+def test_serdes(expr) -> None:
     assert str(parse_expression(expr)) == expr
     assert repr(parse_expression(expr))  # smoke test
 
 
 @pytest.mark.parametrize("expr", BAD_EXPRESSIONS)
-def test_bad_serdes(expr):
+def test_bad_serdes(expr) -> None:
     with pytest.raises(SyntaxError):
         parse_expression(expr)
 
 
-def test_deepcopy_expression():
+def test_deepcopy_expression() -> None:
     deepcopy(parse_expression("1"))
     deepcopy(parse_expression("1 > 2"))
     deepcopy(parse_expression("1 & 2"))
@@ -222,7 +222,7 @@ def test_deepcopy_expression():
     deepcopy(parse_expression("2 if x else 3"))
 
 
-def test_safe_eval():
+def test_safe_eval() -> None:
     expr = "7 > x if x > 2 else 3"
     assert safe_eval(expr, {"x": 3}) is True
     assert safe_eval(expr, {"x": 10}) is False
@@ -237,12 +237,12 @@ def test_safe_eval():
         safe_eval("func(x)")
 
 
-def test_eval_kwargs():
+def test_eval_kwargs() -> None:
     expr = parse_expression("a + b")
     assert expr.eval(a=1, b=2) == 3
     assert expr.eval({"a": 2}, b=2) == 4
 
 
 @pytest.mark.parametrize("expr", GOOD_EXPRESSIONS)
-def test_hash(expr):
+def test_hash(expr) -> None:
     assert isinstance(hash(parse_expression(expr)), int)
diff --git a/tests/test_key_codes.py b/tests/test_key_codes.py
index dcfa4ff..0677519 100644
--- a/tests/test_key_codes.py
+++ b/tests/test_key_codes.py
@@ -7,7 +7,7 @@
 from app_model.types._keys._key_codes import keycode_to_os_name, keycode_to_os_symbol
 
 
-def test_key_codes():
+def test_key_codes() -> None:
     for key in KeyCode:
         assert key == KeyCode.from_string(str(key))
 
@@ -42,12 +42,12 @@ def test_key_codes_to_os(
         assert getattr(key, os_method)(os) == key_map_func(key, os)
 
 
-def test_scan_codes():
+def test_scan_codes() -> None:
     for scan in ScanCode:
         assert scan == ScanCode.from_string(str(scan)), scan
 
 
-def test_key_combo():
+def test_key_combo() -> None:
     """KeyCombo is an integer combination of one or more KeyMod and KeyCode."""
     combo = KeyMod.Shift | KeyMod.Alt | KeyCode.KeyK
     assert repr(combo) == "<KeyCombo.Shift|Alt|KeyK: 1564>"
@@ -55,7 +55,7 @@ def test_key_combo():
     assert kb == SimpleKeyBinding(shift=True, alt=True, key=KeyCode.KeyK)
 
 
-def test_key_chord():
+def test_key_chord() -> None:
     """KeyChord is an integer combination of two KeyCombos, KeyCodes, or integers."""
     chord = KeyChord(KeyMod.CtrlCmd | KeyCode.KeyK, KeyCode.KeyM)
     assert int(chord) == 1968156
diff --git a/tests/test_qt/test_demos.py b/tests/test_qt/test_demos.py
index 0c1960d..45a3fa0 100644
--- a/tests/test_qt/test_demos.py
+++ b/tests/test_qt/test_demos.py
@@ -8,6 +8,6 @@
 
 
 @pytest.mark.parametrize("fname", ["qapplication.py", "model_app.py", "multi_file"])
-def test_qapp(qapp, fname, monkeypatch):
+def test_qapp(qapp, fname, monkeypatch) -> None:
     monkeypatch.setattr(QApplication, "exec_", lambda *a, **k: None)
     runpy.run_path(str(DEMO / fname), run_name="__main__")
diff --git a/tests/test_qt/test_qkeybindingedit.py b/tests/test_qt/test_qkeybindingedit.py
index 749d3c0..e6163c6 100644
--- a/tests/test_qt/test_qkeybindingedit.py
+++ b/tests/test_qt/test_qkeybindingedit.py
@@ -4,7 +4,7 @@
 from app_model.types import KeyBinding, KeyCode, KeyMod
 
 
-def test_qkeysequenceedit(qtbot):
+def test_qkeysequenceedit(qtbot) -> None:
     edit = QModelKeyBindingEdit()
     qtbot.addWidget(edit)
     assert edit.keyBinding() is None
diff --git a/tests/test_qt/test_qmainwindow.py b/tests/test_qt/test_qmainwindow.py
index 6ee2db7..0868595 100644
--- a/tests/test_qt/test_qmainwindow.py
+++ b/tests/test_qt/test_qmainwindow.py
@@ -8,7 +8,7 @@
     from ..conftest import FullApp  # noqa: TID252
 
 
-def test_qmodel_main_window(qtbot, full_app: "FullApp"):
+def test_qmodel_main_window(qtbot, full_app: "FullApp") -> None:
     win = QModelMainWindow(full_app)
     qtbot.addWidget(win)
 
diff --git a/tests/test_registries.py b/tests/test_registries.py
index 10a2ea9..98c39ab 100644
--- a/tests/test_registries.py
+++ b/tests/test_registries.py
@@ -244,7 +244,7 @@ def test_register_action_keybindings_priorization(kb1, kb2, kb3) -> None:
         ),
     ],
 )
-def test_registered_keybinding_comparison(kb1, kb2, gt, lt, eq):
+def test_registered_keybinding_comparison(kb1, kb2, gt, lt, eq) -> None:
     rkb1 = _RegisteredKeyBinding(
         keybinding=kb1["primary"],
         command_id=kb1["command_id"],
diff --git a/tests/test_types.py b/tests/test_types.py
index b8ed9d7..64fdd41 100644
--- a/tests/test_types.py
+++ b/tests/test_types.py
@@ -4,13 +4,13 @@
 from app_model.types import Action, Icon
 
 
-def test_icon_validate():
+def test_icon_validate() -> None:
     assert Icon._validate('"fa6s.arrow_down"') == Icon(
         dark='"fa6s.arrow_down"', light='"fa6s.arrow_down"'
     )
 
 
-def test_action_validation():
+def test_action_validation() -> None:
     with pytest.raises(ValidationError, match="'s!adf' is not a valid python_name"):
         Action(id="test", title="test", callback="s!adf")