diff --git a/.github/workflows/unit_tests.yml b/.github/workflows/unit_tests.yml
index 5654743..6caf8c3 100644
--- a/.github/workflows/unit_tests.yml
+++ b/.github/workflows/unit_tests.yml
@@ -9,13 +9,12 @@ jobs:
       fail-fast: false
       matrix:
         include:
-          - {name: Linux36, python: '3.6', os: ubuntu-latest, tox: py36}
           - {name: Linux37, python: '3.7', os: ubuntu-latest, tox: py37}
           - {name: Linux38, python: '3.8', os: ubuntu-latest, tox: py38}
           - {name: Linux39, python: '3.9', os: ubuntu-latest, tox: py39}
           - {name: Linux310, python: '3.10', os: ubuntu-latest, tox: py310}
-          - {name: Linux311, python: '3.11.0-beta.5', os: ubuntu-latest, tox: py311}
-          - {name: Style, python: '3.10', os: ubuntu-latest, tox: style}
+          - {name: Linux311, python: '3.11', os: ubuntu-latest, tox: py311}
+          - {name: Style, python: '3.11', os: ubuntu-latest, tox: style}
     steps:
     - uses: actions/checkout@v2
     - uses: actions/setup-python@v2
diff --git a/CHANGELOG.md b/CHANGELOG.md
index fcc5098..1e67d3c 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,6 +7,13 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 
 ## [Unreleased]
 
+### Changed
+
+- Add type hints to tests ([#50])
+- Drop explicit support for Python 3.6 ([#48])
+
+## [1.4.0] - 2022-11-08
+
 ### Added
 
 - `inital_text` parameter which, when present, will use logger to log that timer has been started (by [Matthew Price](https://github.com/pricemg) in [#47])
@@ -62,7 +69,8 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 Initial version of `codetiming`. Version 1.0.0 corresponds to the code in the tutorial [Python Timer Functions: Three Ways to Monitor Your Code](https://realpython.com/python-timer/).
 
 
-[Unreleased]: https://github.com/realpython/codetiming/compare/v1.3.2...HEAD
+[Unreleased]: https://github.com/realpython/codetiming/compare/v1.4.0...HEAD
+[1.4.0]: https://github.com/realpython/codetiming/compare/v1.3.2...v1.4.0
 [1.3.2]: https://github.com/realpython/codetiming/compare/v1.3.1...v1.3.2
 [1.3.1]: https://github.com/realpython/codetiming/compare/v1.3.0...v1.3.1
 [1.3.0]: https://github.com/realpython/codetiming/compare/v1.2.0...v1.3.0
@@ -70,19 +78,21 @@ Initial version of `codetiming`. Version 1.0.0 corresponds to the code in the tu
 [1.1.0]: https://github.com/realpython/codetiming/compare/v1.0.0...v1.1.0
 [1.0.0]: https://github.com/realpython/codetiming/releases/tag/v1.0.0
 
-[#13]: https://github.com/realpython/codetiming/pull/13
-[#17]: https://github.com/realpython/codetiming/pull/17
-[#18]: https://github.com/realpython/codetiming/pull/18
-[#23]: https://github.com/realpython/codetiming/pull/23
-[#24]: https://github.com/realpython/codetiming/issues/24
-[#25]: https://github.com/realpython/codetiming/pull/25
-[#27]: https://github.com/realpython/codetiming/pull/27
-[#29]: https://github.com/realpython/codetiming/issues/29
-[#30]: https://github.com/realpython/codetiming/pull/30
-[#32]: https://github.com/realpython/codetiming/pull/32
-[#33]: https://github.com/realpython/codetiming/pull/33
-[#34]: https://github.com/realpython/codetiming/pull/34
-[#35]: https://github.com/realpython/codetiming/pull/35
-[#38]: https://github.com/realpython/codetiming/pull/38
-[#46]: https://github.com/realpython/codetiming/pull/46
+[#50]: https://github.com/realpython/codetiming/pull/50
+[#48]: https://github.com/realpython/codetiming/pull/48
 [#47]: https://github.com/realpython/codetiming/pull/47
+[#46]: https://github.com/realpython/codetiming/pull/46
+[#38]: https://github.com/realpython/codetiming/pull/38
+[#35]: https://github.com/realpython/codetiming/pull/35
+[#34]: https://github.com/realpython/codetiming/pull/34
+[#33]: https://github.com/realpython/codetiming/pull/33
+[#32]: https://github.com/realpython/codetiming/pull/32
+[#30]: https://github.com/realpython/codetiming/pull/30
+[#29]: https://github.com/realpython/codetiming/issues/29
+[#27]: https://github.com/realpython/codetiming/pull/27
+[#25]: https://github.com/realpython/codetiming/pull/25
+[#24]: https://github.com/realpython/codetiming/issues/24
+[#23]: https://github.com/realpython/codetiming/pull/23
+[#18]: https://github.com/realpython/codetiming/pull/18
+[#17]: https://github.com/realpython/codetiming/pull/17
+[#13]: https://github.com/realpython/codetiming/pull/13
diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index 2739d8c..79654c9 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -26,24 +26,20 @@ Do you want to contribute code to `codetiming`? Fantastic! We welcome contributi
 
 ## Setting Up Your Environment
 
-`codetiming` uses [`flit`](https://flit.readthedocs.io) for package management. You should first install `flit`:
+`codetiming` uses [`flit`](https://flit.readthedocs.io) for package management. You can use `flit` through [`pip`](https://realpython.com/what-is-pip/).
 
-```
-$ python -m pip install flit
-```
-
-You can then install `codetiming` locally for development with `flit`:
+You can then install `codetiming` locally for development with `pip`:
 
 ```
-$ python -m flit install --pth-file --deps all
+$ python -m pip install --editable .[dev,test]
 ```
 
-This will install `codetiming` and all its dependencies, including development tools like [`black`](https://black.readthedocs.io) and [`mypy`](http://mypy-lang.org/). The `--pth-file` option allows you to test your changes without reinstalling. On Linux and Mac, you can use `--symlink` for the same effect.
+This will install `codetiming` and all its dependencies, including development tools like [`black`](https://black.readthedocs.io) and [`mypy`](http://mypy-lang.org/), and test runners like [`pytest`](https://docs.pytest.org/). The `--editable` option allows you to test your changes without reinstalling.
 
 
 ## Running Tests
 
-Run tests using [`tox`](https://tox.readthedocs.io/). `tox` helps to enforce the following principles:
+Run tests using [`tox`](https://tox.readthedocs.io/). You can also run individual tests manually. `tox` helps to enforce the following principles:
 
 - Consistent code style using [`black`](https://black.readthedocs.io). You can automatically format your code as follows:
 
@@ -54,7 +50,7 @@ Run tests using [`tox`](https://tox.readthedocs.io/). `tox` helps to enforce the
 - Static type hinting using [`mypy`](http://mypy-lang.org/). Test your type hints as follows:
 
     ```console
-    $ mypy --strict codetiming/
+    $ mypy --strict codetiming/ tests/
     ```
 
     See Real Python's [Python Type Checking guide](https://realpython.com/python-type-checking/) for more information.
@@ -62,10 +58,10 @@ Run tests using [`tox`](https://tox.readthedocs.io/). `tox` helps to enforce the
 - Unit testing using [`pytest`](https://docs.pytest.org/). You can run your tests and see a coverage report as follows:
 
     ```console
-    $ pytest --cov=codetiming --cov-report=term-missing
+    $ python -m pytest --cov=codetiming --cov-report=term-missing
     ```
 
-- Code issues are checked with the [flake8]() linter. You can run flake8 manually as follows:
+- Code issues are checked with the [flake8](https://flake8.pycqa.org/) linter. You can run flake8 manually as follows:
 
     ```console
     $ python -m flake8 codetiming/ tests/
@@ -80,7 +76,7 @@ Run tests using [`tox`](https://tox.readthedocs.io/). `tox` helps to enforce the
 - All modules, functions, classes, and methods must have docstrings. This is enforced by [Interrogation](https://interrogate.readthedocs.io/). You can test compliance as follows:
 
     ```console
-    $ interrogate -c pyproject.toml -vv
+    $ python -m interrogate -c pyproject.toml -vv
     ```
 
-Feel free to ask for help in your PR if you are having challenges with any of these tests.
\ No newline at end of file
+Feel free to ask for help in your PR if you are having challenges with any of these tests.
diff --git a/codetiming/_timer.py b/codetiming/_timer.py
index 4b218af..21a2796 100644
--- a/codetiming/_timer.py
+++ b/codetiming/_timer.py
@@ -9,12 +9,32 @@
 import time
 from contextlib import ContextDecorator
 from dataclasses import dataclass, field
-from typing import Any, Callable, ClassVar, Optional, Union
+from typing import TYPE_CHECKING, Any, Callable, ClassVar, Optional, Union
 
 # Codetiming imports
 from codetiming._timers import Timers
 
+# Special types, Protocol only works for Python >= 3.8
+if TYPE_CHECKING:  # pragma: nocover
+    # Standard library imports
+    from typing import Protocol, TypeVar
 
+    T = TypeVar("T")
+
+    class FloatArg(Protocol):
+        """Protocol type that allows classes that take one float argument"""
+
+        def __call__(self: T, __seconds: float) -> T:
+            """Callable signature"""
+            ...  # pragma: nocover
+
+else:
+
+    class FloatArg:
+        """Dummy runtime class"""
+
+
+# Timer code
 class TimerError(Exception):
     """A custom exception used to report errors in use of Timer class."""
 
@@ -24,12 +44,12 @@ class Timer(ContextDecorator):
     """Time your code using a class, context manager, or decorator."""
 
     timers: ClassVar[Timers] = Timers()
-    _start_time: Optional[float] = field(default=None, init=False, repr=False)
     name: Optional[str] = None
-    text: Union[str, Callable[[float], str]] = "Elapsed time: {:0.4f} seconds"
-    initial_text: Union[bool, str] = False
+    text: Union[str, FloatArg, Callable[[float], str]] = "Elapsed time: {:0.4f} seconds"
+    initial_text: Union[bool, str, FloatArg] = False
     logger: Optional[Callable[[str], None]] = print
     last: float = field(default=math.nan, init=False, repr=False)
+    _start_time: Optional[float] = field(default=None, init=False, repr=False)
 
     def start(self) -> None:
         """Start a new timer."""
@@ -69,7 +89,7 @@ def stop(self) -> float:
                     "minutes": self.last / 60,
                 }
                 text = self.text.format(self.last, **attributes)
-            self.logger(text)
+            self.logger(str(text))
         if self.name:
             self.timers.add(self.name, self.last)
 
diff --git a/pyproject.toml b/pyproject.toml
index 7ac01fc..e9ddd8f 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -18,7 +18,6 @@ classifiers = [
     "Operating System :: MacOS",
     "Operating System :: Microsoft",
     "Operating System :: POSIX :: Linux",
-    "Programming Language :: Python :: 3.6",
     "Programming Language :: Python :: 3.7",
     "Programming Language :: Python :: 3.8",
     "Programming Language :: Python :: 3.9",
@@ -30,8 +29,8 @@ classifiers = [
     "Typing :: Typed",
 ]
 keywords = ["timer", "class", "contextmanager", "decorator"]
-requires-python = ">=3.6"
-dependencies = ["dataclasses; python_version < '3.7'"]
+requires-python = ">=3.7"
+dependencies = []
 
 [project.urls]
 Homepage      = "https://realpython.com/python-timer"
diff --git a/tests/test_codetiming.py b/tests/test_codetiming.py
index c9502c8..d74a7bb 100644
--- a/tests/test_codetiming.py
+++ b/tests/test_codetiming.py
@@ -27,31 +27,31 @@
 )
 
 
-def waste_time(num=1000):
+def waste_time(num: int = 1000) -> None:
     """Just waste a little bit of time."""
     sum(n**2 for n in range(num))
 
 
 @Timer(text=TIME_MESSAGE)
-def decorated_timewaste(num=1000):
+def decorated_timewaste(num: int = 1000) -> None:
     """Just waste a little bit of time."""
     sum(n**2 for n in range(num))
 
 
 @Timer(text=TIME_MESSAGE, initial_text=True)
-def decorated_timewaste_initial_text_true(num=1000):
+def decorated_timewaste_initial_text_true(num: int = 1000) -> None:
     """Just waste a little bit of time."""
     sum(n**2 for n in range(num))
 
 
 @Timer(text=TIME_MESSAGE, initial_text="Starting the party")
-def decorated_timewaste_initial_text_custom(num=1000):
+def decorated_timewaste_initial_text_custom(num: int = 1000) -> None:
     """Just waste a little bit of time."""
     sum(n**2 for n in range(num))
 
 
 @Timer(name="accumulator", text=TIME_MESSAGE)
-def accumulated_timewaste(num=1000):
+def accumulated_timewaste(num: int = 1000) -> None:
     """Just waste a little bit of time."""
     sum(n**2 for n in range(num))
 
@@ -59,11 +59,11 @@ def accumulated_timewaste(num=1000):
 class CustomLogger:
     """Simple class used to test custom logging capabilities in Timer."""
 
-    def __init__(self):
+    def __init__(self) -> None:
         """Store log messages in the .messages attribute."""
         self.messages = ""
 
-    def __call__(self, message):
+    def __call__(self, message: str) -> None:
         """Add a log message to the .messages attribute."""
         self.messages += message
 
@@ -71,7 +71,7 @@ def __call__(self, message):
 #
 # Tests
 #
-def test_timer_as_decorator(capsys):
+def test_timer_as_decorator(capsys: pytest.CaptureFixture[str]) -> None:
     """Test that decorated function prints timing information."""
     decorated_timewaste()
 
@@ -81,7 +81,7 @@ def test_timer_as_decorator(capsys):
     assert stderr == ""
 
 
-def test_timer_as_context_manager(capsys):
+def test_timer_as_context_manager(capsys: pytest.CaptureFixture[str]) -> None:
     """Test that timed context prints timing information."""
     with Timer(text=TIME_MESSAGE):
         waste_time()
@@ -92,7 +92,7 @@ def test_timer_as_context_manager(capsys):
     assert stderr == ""
 
 
-def test_explicit_timer(capsys):
+def test_explicit_timer(capsys: pytest.CaptureFixture[str]) -> None:
     """Test that timed section prints timing information."""
     t = Timer(text=TIME_MESSAGE)
     t.start()
@@ -105,22 +105,23 @@ def test_explicit_timer(capsys):
     assert stderr == ""
 
 
-def test_error_if_timer_not_running():
+def test_error_if_timer_not_running() -> None:
     """Test that timer raises error if it is stopped before started."""
     t = Timer(text=TIME_MESSAGE)
     with pytest.raises(TimerError):
         t.stop()
 
 
-def test_access_timer_object_in_context(capsys):
+def test_access_timer_object_in_context(capsys: pytest.CaptureFixture[str]) -> None:
     """Test that we can access the timer object inside a context."""
     with Timer(text=TIME_MESSAGE) as t:
         assert isinstance(t, Timer)
+        assert isinstance(t.text, str)
         assert t.text.startswith(TIME_PREFIX)
     _, _ = capsys.readouterr()  # Do not print log message to standard out
 
 
-def test_custom_logger():
+def test_custom_logger() -> None:
     """Test that we can use a custom logger."""
     logger = CustomLogger()
     with Timer(text=TIME_MESSAGE, logger=logger):
@@ -128,7 +129,7 @@ def test_custom_logger():
     assert RE_TIME_MESSAGE.match(logger.messages)
 
 
-def test_timer_without_text(capsys):
+def test_timer_without_text(capsys: pytest.CaptureFixture[str]) -> None:
     """Test that timer with logger=None does not print anything."""
     with Timer(logger=None):
         waste_time()
@@ -138,7 +139,7 @@ def test_timer_without_text(capsys):
     assert stderr == ""
 
 
-def test_accumulated_decorator(capsys):
+def test_accumulated_decorator(capsys: pytest.CaptureFixture[str]) -> None:
     """Test that decorated timer can accumulate."""
     accumulated_timewaste()
     accumulated_timewaste()
@@ -151,7 +152,7 @@ def test_accumulated_decorator(capsys):
     assert stderr == ""
 
 
-def test_accumulated_context_manager(capsys):
+def test_accumulated_context_manager(capsys: pytest.CaptureFixture[str]) -> None:
     """Test that context manager timer can accumulate."""
     t = Timer(name="accumulator", text=TIME_MESSAGE)
     with t:
@@ -167,10 +168,10 @@ def test_accumulated_context_manager(capsys):
     assert stderr == ""
 
 
-def test_accumulated_explicit_timer(capsys):
+def test_accumulated_explicit_timer(capsys: pytest.CaptureFixture[str]) -> None:
     """Test that explicit timer can accumulate."""
     t = Timer(name="accumulated_explicit_timer", text=TIME_MESSAGE)
-    total = 0
+    total = 0.0
     t.start()
     waste_time()
     total += t.stop()
@@ -187,7 +188,7 @@ def test_accumulated_explicit_timer(capsys):
     assert total == Timer.timers["accumulated_explicit_timer"]
 
 
-def test_error_if_restarting_running_timer():
+def test_error_if_restarting_running_timer() -> None:
     """Test that restarting a running timer raises an error."""
     t = Timer(text=TIME_MESSAGE)
     t.start()
@@ -195,21 +196,23 @@ def test_error_if_restarting_running_timer():
         t.start()
 
 
-def test_last_starts_as_nan():
+def test_last_starts_as_nan() -> None:
     """Test that .last attribute is initialized as nan."""
     t = Timer()
     assert math.isnan(t.last)
 
 
-def test_timer_sets_last():
+def test_timer_sets_last() -> None:
     """Test that .last attribute is properly set."""
-    with Timer() as t:
+    with Timer(logger=None) as t:
         time.sleep(0.02)
 
     assert t.last >= 0.02
 
 
-def test_using_name_in_text_without_explicit_timer(capsys):
+def test_using_name_in_text_without_explicit_timer(
+    capsys: pytest.CaptureFixture[str],
+) -> None:
     """Test that the name of the timer can be referenced in the text."""
     name = "NamedTimer"
     with Timer(name=name, text="{name}: {:.2f}"):
@@ -220,7 +223,9 @@ def test_using_name_in_text_without_explicit_timer(capsys):
     assert stderr == ""
 
 
-def test_using_name_in_text_with_explicit_timer(capsys):
+def test_using_name_in_text_with_explicit_timer(
+    capsys: pytest.CaptureFixture[str],
+) -> None:
     """Test that timer name and seconds attribute can be referenced in the text."""
     name = "NamedTimer"
     with Timer(name=name, text="{name}: {seconds:.2f}"):
@@ -231,7 +236,7 @@ def test_using_name_in_text_with_explicit_timer(capsys):
     assert stderr == ""
 
 
-def test_using_minutes_attribute_in_text(capsys):
+def test_using_minutes_attribute_in_text(capsys: pytest.CaptureFixture[str]) -> None:
     """Test that timer can report its duration in minutes."""
     with Timer(text="{minutes:.1f} minutes"):
         waste_time()
@@ -241,7 +246,9 @@ def test_using_minutes_attribute_in_text(capsys):
     assert stderr == ""
 
 
-def test_using_milliseconds_attribute_in_text(capsys):
+def test_using_milliseconds_attribute_in_text(
+    capsys: pytest.CaptureFixture[str],
+) -> None:
     """Test that timer can report its duration in milliseconds."""
     with Timer(text="{milliseconds:.0f} {seconds:.3f}"):
         waste_time()
@@ -252,10 +259,10 @@ def test_using_milliseconds_attribute_in_text(capsys):
     assert stderr == ""
 
 
-def test_text_formatting_function(capsys):
+def test_text_formatting_function(capsys: pytest.CaptureFixture[str]) -> None:
     """Test that text can be formatted by a separate function."""
 
-    def format_text(seconds):
+    def format_text(seconds: float) -> str:
         """Function that returns a formatted text"""
         return f"Function: {seconds + 1:.0f}"
 
@@ -267,17 +274,17 @@ def format_text(seconds):
     assert not stderr.strip()
 
 
-def test_text_formatting_class(capsys):
+def test_text_formatting_class(capsys: pytest.CaptureFixture[str]) -> None:
     """Test that text can be formatted by a separate class."""
 
     class TextFormatter:
         """Class that behaves like a formatted text."""
 
-        def __init__(self, seconds):
-            """Initialize with number of seconds"""
+        def __init__(self, seconds: float) -> None:
+            """Store the elapsed number of seconds"""
             self.seconds = seconds
 
-        def __str__(self):
+        def __str__(self) -> str:
             """Represent the class as a formatted text"""
             return f"Class: {self.seconds + 1:.0f}"
 
@@ -289,9 +296,9 @@ def __str__(self):
     assert not stderr.strip()
 
 
-def test_timers_cleared():
+def test_timers_cleared() -> None:
     """Test that timers can be cleared."""
-    with Timer(name="timer_to_be_cleared"):
+    with Timer(name="timer_to_be_cleared", logger=None):
         waste_time()
 
     assert "timer_to_be_cleared" in Timer.timers
@@ -299,7 +306,7 @@ def test_timers_cleared():
     assert not Timer.timers
 
 
-def test_running_cleared_timers():
+def test_running_cleared_timers(capsys: pytest.CaptureFixture[str]) -> None:
     """Test that timers can still be run after they're cleared."""
     t = Timer(name="timer_to_be_cleared")
     Timer.timers.clear()
@@ -308,14 +315,15 @@ def test_running_cleared_timers():
     with t:
         waste_time()
 
+    capsys.readouterr()
     assert "accumulator" in Timer.timers
     assert "timer_to_be_cleared" in Timer.timers
 
 
-def test_timers_stats():
+def test_timers_stats() -> None:
     """Test that we can get basic statistics from timers."""
     name = "timer_with_stats"
-    t = Timer(name=name)
+    t = Timer(name=name, logger=None)
     for num in range(5, 10):
         with t:
             waste_time(num=100 * num)
@@ -328,7 +336,7 @@ def test_timers_stats():
     assert stats.stdev(name) >= 0
 
 
-def test_stats_missing_timers():
+def test_stats_missing_timers() -> None:
     """Test that getting statistics from non-existent timers raises exception."""
     with pytest.raises(KeyError):
         Timer.timers.count("non_existent_timer")
@@ -337,13 +345,15 @@ def test_stats_missing_timers():
         Timer.timers.stdev("non_existent_timer")
 
 
-def test_setting_timers_exception():
+def test_setting_timers_exception() -> None:
     """Test that setting .timers items raises exception."""
     with pytest.raises(TypeError):
         Timer.timers["set_timer"] = 1.23
 
 
-def test_timer_as_decorator_with_initial_text_true(capsys):
+def test_timer_as_decorator_with_initial_text_true(
+    capsys: pytest.CaptureFixture[str],
+) -> None:
     """Test that decorated function prints at start with default initial text."""
     decorated_timewaste_initial_text_true()
 
@@ -353,7 +363,9 @@ def test_timer_as_decorator_with_initial_text_true(capsys):
     assert stderr == ""
 
 
-def test_timer_as_context_manager_with_initial_text_true(capsys):
+def test_timer_as_context_manager_with_initial_text_true(
+    capsys: pytest.CaptureFixture[str],
+) -> None:
     """Test that timed context prints at start with default initial text."""
     with Timer(text=TIME_MESSAGE, initial_text=True):
         waste_time()
@@ -364,7 +376,9 @@ def test_timer_as_context_manager_with_initial_text_true(capsys):
     assert stderr == ""
 
 
-def test_explicit_timer_with_initial_text_true(capsys):
+def test_explicit_timer_with_initial_text_true(
+    capsys: pytest.CaptureFixture[str],
+) -> None:
     """Test that timed section prints at start with default initial text."""
     t = Timer(text=TIME_MESSAGE, initial_text=True)
     t.start()
@@ -377,7 +391,9 @@ def test_explicit_timer_with_initial_text_true(capsys):
     assert stderr == ""
 
 
-def test_timer_as_decorator_with_initial_text_custom(capsys):
+def test_timer_as_decorator_with_initial_text_custom(
+    capsys: pytest.CaptureFixture[str],
+) -> None:
     """Test that decorated function prints at start with custom initial text."""
     decorated_timewaste_initial_text_custom()
 
@@ -387,7 +403,9 @@ def test_timer_as_decorator_with_initial_text_custom(capsys):
     assert stderr == ""
 
 
-def test_timer_as_context_manager_with_initial_text_custom(capsys):
+def test_timer_as_context_manager_with_initial_text_custom(
+    capsys: pytest.CaptureFixture[str],
+) -> None:
     """Test that timed context prints at start with custom initial text."""
     with Timer(text=TIME_MESSAGE, initial_text="Starting the party"):
         waste_time()
@@ -398,7 +416,9 @@ def test_timer_as_context_manager_with_initial_text_custom(capsys):
     assert stderr == ""
 
 
-def test_explicit_timer_with_initial_text_custom(capsys):
+def test_explicit_timer_with_initial_text_custom(
+    capsys: pytest.CaptureFixture[str],
+) -> None:
     """Test that timed section prints at start with custom initial text."""
     t = Timer(text=TIME_MESSAGE, initial_text="Starting the party")
     t.start()
@@ -411,7 +431,9 @@ def test_explicit_timer_with_initial_text_custom(capsys):
     assert stderr == ""
 
 
-def test_explicit_timer_with_initial_text_true_with_name(capsys):
+def test_explicit_timer_with_initial_text_true_with_name(
+    capsys: pytest.CaptureFixture[str],
+) -> None:
     """Test with default initial text referencing timer name."""
     t = Timer(name="named", text=TIME_MESSAGE, initial_text=True)
     t.start()
@@ -426,7 +448,9 @@ def test_explicit_timer_with_initial_text_true_with_name(capsys):
     assert stderr == ""
 
 
-def test_explicit_timer_with_initial_text_with_name(capsys):
+def test_explicit_timer_with_initial_text_with_name(
+    capsys: pytest.CaptureFixture[str],
+) -> None:
     """Test with custom initial text referencing timer name."""
     t = Timer(name="the party", text=TIME_MESSAGE, initial_text="Starting {name}")
     t.start()
diff --git a/tox.ini b/tox.ini
index 55cc473..10119a0 100644
--- a/tox.ini
+++ b/tox.ini
@@ -19,9 +19,10 @@ deps =
     interrogate
     isort
     mypy
+    pytest
 commands = 
     {envpython} -m black --check --quiet codetiming/ tests/
     {envpython} -m flake8 codetiming/ tests/
     {envpython} -m interrogate --quiet --config=pyproject.toml
     {envpython} -m isort --check codetiming/ tests/
-    {envpython} -m mypy --strict codetiming/
+    {envpython} -m mypy --strict codetiming/ tests/