diff --git a/.github/workflows/tox.yml b/.github/workflows/tox.yml
index 0146a10..27cc0b7 100644
--- a/.github/workflows/tox.yml
+++ b/.github/workflows/tox.yml
@@ -1,6 +1,6 @@
 name: tox
 
-on: [push, pull_request]
+on: [ push, pull_request ]
 
 jobs:
   tox:
@@ -8,7 +8,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        python-version: ["3.9", "3.10", "3.11", "3.12"]
+        python-version: [ "3.9", "3.10", "3.11", "3.12", "3.13" ]
 
     steps:
       - uses: actions/checkout@v4
@@ -16,7 +16,7 @@ jobs:
       - name: Install uv
         uses: astral-sh/setup-uv@v3
         with:
-          version: "0.4.18"
+          version: "0.5"
           enable-cache: true
 
       - name: Set up Python ${{ matrix.python-version }}
diff --git a/.gitignore b/.gitignore
index d01cff3..a41c0c0 100644
--- a/.gitignore
+++ b/.gitignore
@@ -55,4 +55,6 @@ MANIFEST
 .epg_data/*
 
 # uv
-.python-version
\ No newline at end of file
+.python-version
+
+.venv/
\ No newline at end of file
diff --git a/aiocron/__init__.py b/aiocron/__init__.py
index de9df35..a8e4a47 100644
--- a/aiocron/__init__.py
+++ b/aiocron/__init__.py
@@ -3,22 +3,24 @@
 from datetime import datetime
 from functools import wraps, partial
 from tzlocal import get_localzone
-from uuid import uuid4
+from uuid import uuid4, UUID
 import time
 import asyncio
 import sys
 import inspect
+import typing as tp
+import zoneinfo
 
 
-async def null_callback(*args):
+async def null_callback(*args: tp.Any) -> tp.Tuple[tp.Any, ...]:
     return args
 
 
-def wrap_func(func):
+def wrap_func(func: tp.Callable[..., tp.Union[tp.Any, tp.Awaitable[tp.Any]]]) -> tp.Callable[..., tp.Awaitable[tp.Any]]:
     """wrap in a coroutine"""
 
     @wraps(func)
-    async def wrapper(*args, **kwargs):
+    async def wrapper(*args: tp.Any, **kwargs: tp.Any) -> tp.Any:
         result = func(*args, **kwargs)
         if inspect.isawaitable(result):
             result = await result
@@ -30,15 +32,15 @@ async def wrapper(*args, **kwargs):
 class Cron(object):
     def __init__(
         self,
-        spec,
-        func=None,
-        args=(),
-        kwargs=None,
-        start=False,
-        uuid=None,
-        loop=None,
-        tz=None,
-    ):
+        spec: str,
+        func: tp.Optional[tp.Callable[..., tp.Union[tp.Any, tp.Awaitable[tp.Any]]]] = None,
+        args: tp.Tuple[tp.Any, ...] = (),
+        kwargs: tp.Optional[tp.Mapping[str, tp.Any]] = None,
+        start: bool = False,
+        uuid: tp.Optional[UUID] = None,
+        loop: tp.Optional[asyncio.AbstractEventLoop] = None,
+        tz: tp.Optional[zoneinfo.ZoneInfo] = None,
+    ) -> None:
         self.spec = spec
         if func is not None:
             kwargs = kwargs or {}
@@ -46,34 +48,36 @@ def __init__(
         else:
             self.func = null_callback
         self.tz = get_localzone() if tz is None else tz
-        self.cron = wrap_func(self.func)
+        self.cron: tp.Callable[..., tp.Awaitable[tp.Any]] = wrap_func(self.func)
         self.auto_start = start
         self.uuid = uuid if uuid is not None else uuid4()
-        self.handle = self.future = self.cronsim = None
+        self.handle = None
+        self.future: tp.Optional[asyncio.Future] = None
+        self.cronsim: tp.Optional[CronSim] = None
         self.loop = loop if loop is not None else asyncio.get_event_loop()
         if start and self.func is not null_callback:
             self.handle = self.loop.call_soon_threadsafe(self.start)
 
-    def start(self):
+    def start(self) -> None:
         """Start scheduling"""
         self.stop()
         self.initialize()
         self.handle = self.loop.call_at(self.get_next(), self.call_next)
 
-    def stop(self):
+    def stop(self) -> None:
         """Stop scheduling"""
         if self.handle is not None:
             self.handle.cancel()
         self.handle = self.future = self.cronsim = None
 
-    async def next(self, *args):
+    async def next(self, *args: tp.Any) -> tp.Any:
         """yield from .next()"""
         self.initialize()
         self.future = asyncio.Future(loop=self.loop)
         self.handle = self.loop.call_at(self.get_next(), self.call_func, *args)
         return await self.future
 
-    def initialize(self):
+    def initialize(self) -> None:
         """Initialize cronsim and related times"""
         if self.cronsim is None:
             self.time = time.time()
@@ -81,11 +85,11 @@ def initialize(self):
             self.loop_time = self.loop.time()
             self.cronsim = CronSim(self.spec, self.datetime)
 
-    def get_next(self):
+    def get_next(self) -> float:
         """Return next iteration time related to loop time"""
         return self.loop_time + (next(self.cronsim).timestamp() - self.time)
 
-    def call_next(self):
+    def call_next(self) -> None:
         """Set next hop in the loop. Call task"""
         if self.handle is not None:
             self.handle.cancel()
@@ -93,7 +97,7 @@ def call_next(self):
         self.handle = self.loop.call_at(next_time, self.call_next)
         self.call_func()
 
-    def call_func(self, *args, **kwargs):
+    def call_func(self, *args: tp.Any, **kwargs: tp.Any) -> None:
         """Called. Take care of exceptions using gather"""
         """Check the version of python installed"""
         if sys.version_info[0:2] >= (3, 10):
@@ -105,7 +109,7 @@ def call_func(self, *args, **kwargs):
                 self.cron(*args, **kwargs), loop=self.loop, return_exceptions=True
             ).add_done_callback(self.set_result)
 
-    def set_result(self, result):
+    def set_result(self, result: asyncio.Future) -> None:
         """Set future's result if needed (can be an exception).
         Else raise if needed."""
         result = result.result()[0]
@@ -118,7 +122,7 @@ def set_result(self, result):
         elif isinstance(result, Exception):
             raise result
 
-    def __call__(self, func):
+    def __call__(self, func: tp.Callable[..., tp.Awaitable[tp.Any]]) -> 'Cron':
         """Used as a decorator"""
         self.func = func
         self.cron = wrap_func(func)
@@ -126,14 +130,22 @@ def __call__(self, func):
             self.loop.call_soon_threadsafe(self.start)
         return self
 
-    def __str__(self):
+    def __str__(self) -> str:
         return "{0.spec} {0.func}".format(self)
 
-    def __repr__(self):
+    def __repr__(self) -> str:
         return "<Cron {0.spec} {0.func}>".format(self)
 
 
-def crontab(spec, func=None, args=(), kwargs=None, start=True, loop=None, tz=None):
+def crontab(
+    spec: str,
+    func: tp.Optional[tp.Callable[..., tp.Union[tp.Any, tp.Awaitable[tp.Any]]]] = None,
+    args: tp.Tuple[tp.Any, ...] = (),
+    kwargs: tp.Optional[tp.Mapping[str, tp.Any]] = None,
+    start: bool = False,
+    loop: tp.Optional[asyncio.AbstractEventLoop] = None,
+    tz: tp.Optional[zoneinfo.ZoneInfo] = None,
+) -> Cron:
     return Cron(
         spec, func=func, args=args, kwargs=kwargs, start=start, loop=loop, tz=tz
     )
diff --git a/aiocron/__main__.py b/aiocron/__main__.py
index 5b812e4..65e6261 100644
--- a/aiocron/__main__.py
+++ b/aiocron/__main__.py
@@ -6,7 +6,7 @@
 import argparse
 
 
-def main():
+def main() -> None:
     parser = argparse.ArgumentParser()
     parser.prog = "python -m aiocron"
     parser.add_argument(
diff --git a/pyproject.toml b/pyproject.toml
index 39ea351..3ad1785 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -18,6 +18,7 @@ classifiers = [
     "Programming Language :: Python :: 3.10",
     "Programming Language :: Python :: 3.11",
     "Programming Language :: Python :: 3.12",
+    "Programming Language :: Python :: 3.13",
     "License :: OSI Approved :: MIT License",
     "Topic :: Software Development :: Libraries :: Python Modules",
 ]
@@ -47,7 +48,6 @@ build-backend = "setuptools.build_meta"
 [tool.setuptools]
 packages = ["aiocron"]
 
-
 [tool.pytest.ini_options]
 addopts = "--cov aiocron --cov-report term-missing"
 testpaths = ["tests"]
diff --git a/uv.lock b/uv.lock
index 9fde648..432de62 100644
--- a/uv.lock
+++ b/uv.lock
@@ -11,17 +11,14 @@ name = "aiocron"
 version = "1.9.dev0"
 source = { editable = "." }
 dependencies = [
-    { name = "croniter" },
+    { name = "cronsim" },
+    { name = "python-dateutil" },
     { name = "tox" },
     { name = "tox-uv" },
     { name = "tzlocal" },
 ]
 
 [package.optional-dependencies]
-coverage = [
-    { name = "pytest" },
-    { name = "pytest-cov" },
-]
 test = [
     { name = "coverage" },
     { name = "pytest" },
@@ -31,11 +28,10 @@ test = [
 [package.metadata]
 requires-dist = [
     { name = "coverage", marker = "extra == 'test'", specifier = ">=7.6.1" },
-    { name = "croniter", specifier = ">=3.0.3" },
-    { name = "pytest", marker = "extra == 'coverage'", specifier = ">=8.3.3" },
+    { name = "cronsim", specifier = ">=2.6" },
     { name = "pytest", marker = "extra == 'test'", specifier = ">=8.3.3" },
-    { name = "pytest-cov", marker = "extra == 'coverage'", specifier = ">=5.0.0" },
     { name = "pytest-cov", marker = "extra == 'test'", specifier = ">=5.0.0" },
+    { name = "python-dateutil", specifier = ">=2.9.0" },
     { name = "tox", specifier = ">=4.21.1" },
     { name = "tox-uv", specifier = ">=1.13.0" },
     { name = "tzlocal", specifier = ">=5.2" },
@@ -143,16 +139,12 @@ toml = [
 ]
 
 [[package]]
-name = "croniter"
-version = "3.0.3"
+name = "cronsim"
+version = "2.6"
 source = { registry = "https://pypi.org/simple" }
-dependencies = [
-    { name = "python-dateutil" },
-    { name = "pytz" },
-]
-sdist = { url = "https://files.pythonhosted.org/packages/44/7a/14b0b14ab0203e2c79493cf487829dc294d5c44bedc810ab2f4a97fc9ff4/croniter-3.0.3.tar.gz", hash = "sha256:34117ec1741f10a7bd0ec3ad7d8f0eb8fa457a2feb9be32e6a2250e158957668", size = 53088 }
+sdist = { url = "https://files.pythonhosted.org/packages/5b/d8/cfb8d51a51f6076ffa09902c02978c7db9764cca78f4ee832e691d20f44b/cronsim-2.6.tar.gz", hash = "sha256:5aab98716ef90ab5ac6be294b2c3965dbf76dc869f048846a0af74ebb506c10d", size = 20315 }
 wheels = [
-    { url = "https://files.pythonhosted.org/packages/93/6a/f2f68e0f9cf702b6d055ab53cab0d8c100f04e86228ca500a8ca9de94b58/croniter-3.0.3-py2.py3-none-any.whl", hash = "sha256:b3bd11f270dc54ccd1f2397b813436015a86d30ffc5a7a9438eec1ed916f2101", size = 22422 },
+    { url = "https://files.pythonhosted.org/packages/8c/dd/9c40c4e0f4d3cb6cf52eb335e9cc1fa140c1f3a87146fb6987f465b069da/cronsim-2.6-py3-none-any.whl", hash = "sha256:5e153ff8ed64da7ee8d5caac470dbeda8024ab052c3010b1be149772b4801835", size = 13500 },
 ]
 
 [[package]]
@@ -273,15 +265,6 @@ wheels = [
     { url = "https://files.pythonhosted.org/packages/ec/57/56b9bcc3c9c6a792fcbaf139543cee77261f3651ca9da0c93f5c1221264b/python_dateutil-2.9.0.post0-py2.py3-none-any.whl", hash = "sha256:a8b2bc7bffae282281c8140a97d3aa9c14da0b136dfe83f850eea9a5f7470427", size = 229892 },
 ]
 
-[[package]]
-name = "pytz"
-version = "2024.2"
-source = { registry = "https://pypi.org/simple" }
-sdist = { url = "https://files.pythonhosted.org/packages/3a/31/3c70bf7603cc2dca0f19bdc53b4537a797747a58875b552c8c413d963a3f/pytz-2024.2.tar.gz", hash = "sha256:2aa355083c50a0f93fa581709deac0c9ad65cca8a9e9beac660adcbd493c798a", size = 319692 }
-wheels = [
-    { url = "https://files.pythonhosted.org/packages/11/c3/005fcca25ce078d2cc29fd559379817424e94885510568bc1bc53d7d5846/pytz-2024.2-py2.py3-none-any.whl", hash = "sha256:31c7c1817eb7fae7ca4b8c7ee50c72f93aa2dd863de768e1ef4245d426aa0725", size = 508002 },
-]
-
 [[package]]
 name = "six"
 version = "1.16.0"