diff --git a/.github/workflows/pytest.yml b/.github/workflows/pytest.yml
index 646ef91..1c57d08 100644
--- a/.github/workflows/pytest.yml
+++ b/.github/workflows/pytest.yml
@@ -1,4 +1,4 @@
-name: Run pytest
+name: Tests
 
 on:
   pull_request:
@@ -9,14 +9,23 @@ jobs:
   test:
     runs-on: ubuntu-latest
 
+    strategy:
+      matrix:
+        python-version: ['3.11', '3.10']
+
     steps:
       - name: Checkout code
         uses: actions/checkout@v2
 
+      - name: Set up Python ${{ matrix.python-version }}
+        uses: actions/setup-python@v2
+        with:
+          python-version: ${{ matrix.python-version }}
+
       - name: Install dependencies
         run: |
           python -m pip install --upgrade pip
-          pip install pytest
+          pip install tox
 
-      - name: Run pytest
-        run: pytest
+      - name: Run tox
+        run: tox
diff --git a/README.md b/README.md
index 44bdba0..cf0a451 100644
--- a/README.md
+++ b/README.md
@@ -54,6 +54,8 @@ Install via the extensions tab on the [AUTOMATIC1111 webui](https://github.com/A
 
 Developed using existing [AUTOMATIC1111 webui](https://github.com/AUTOMATIC1111/stable-diffusion-webui) dependencies.
 
+It's recommended to use the python version specified by A111 webui.
+
 However - for running unit tests, we use pytest.
 
 ```bash
diff --git a/aspect_ratio_helper/_components.py b/aspect_ratio_helper/_components.py
index 22530c0..be6a139 100644
--- a/aspect_ratio_helper/_components.py
+++ b/aspect_ratio_helper/_components.py
@@ -1,6 +1,7 @@
 from abc import ABC
 from abc import abstractmethod
 from functools import partial
+from typing import Callable
 
 import gradio as gr
 
@@ -190,7 +191,7 @@ class PredefinedAspectRatioButtons(ArhUIComponent):
         )
 
     @property
-    def display_func(self) -> callable:
+    def display_func(self) -> Callable[[str], str]:
         return lambda _: None  # todo: different displays for aspect ratios.
 
 
@@ -268,7 +269,7 @@ class PredefinedPercentageButtons(ArhUIComponent):
         )
 
     @property
-    def display_func(self) -> callable:
+    def display_func(self) -> Callable[[str], str]:
         return _settings.PREDEFINED_PERCENTAGES_DISPLAY_MAP.get(
             _settings.safe_opt(
                 _constants.ARH_PREDEFINED_PERCENTAGES_DISPLAY_KEY,
diff --git a/aspect_ratio_helper/_util.py b/aspect_ratio_helper/_util.py
index f8850ef..c311fd4 100644
--- a/aspect_ratio_helper/_util.py
+++ b/aspect_ratio_helper/_util.py
@@ -3,7 +3,7 @@ import contextlib
 import aspect_ratio_helper._constants as _const
 
 
-def safe_opt_util(shared_opts, key, default_key_map):
+def safe_opt_util(shared_opts, key, default_key_map: dict[str, object]):
     # attempt to retrieve key from shared options
     with contextlib.suppress(AttributeError):
         value = shared_opts.__getattr__(key)
diff --git a/tox.ini b/tox.ini
new file mode 100644
index 0000000..4c6cac4
--- /dev/null
+++ b/tox.ini
@@ -0,0 +1,6 @@
+[tox]
+envlist = py310, py311
+
+[testenv]
+deps = pytest
+commands = pytest