diff --git a/.github/workflows/auto_test.yml b/.github/workflows/auto_test.yml
index f0cca20..9569cdd 100644
--- a/.github/workflows/auto_test.yml
+++ b/.github/workflows/auto_test.yml
@@ -42,7 +42,7 @@ jobs:
       - name: Install dependencies
         run: |
           python -m pip install --upgrade pip
-          python -m pip install -e .[testing]
+          python -m pip install -e .[testing,type_checking]
       - name: Check type stub files
         run: |
           python -m mypy.stubtest ducktools.classbuilder
diff --git a/pyproject.toml b/pyproject.toml
index 011de4e..606160d 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -27,6 +27,12 @@ classifiers = [
 dynamic = ['version']
 license = {file = "LICENSE.md"}
 
+[project.optional-dependencies]
+testing = ["pytest>=8.2", "pytest-cov", "typing_extensions"]
+type_checking = ["mypy"]
+performance_tests = ["attrs", "pydantic"]
+docs = ["sphinx", "myst-parser", "sphinx_rtd_theme"]
+
 [tool.setuptools.packages.find]
 where = ["src"]
 
@@ -34,12 +40,6 @@ where = ["src"]
 version_file = "src/ducktools/classbuilder/_version.py"
 version_file_template = "__version__ = \"{version}\"\n__version_tuple__ = {version_tuple}\n"
 
-
-[project.optional-dependencies]
-testing = ["pytest>=8.2", "pytest-cov", "mypy", "typing_extensions"]
-performance_tests = ["attrs", "pydantic"]
-docs = ["sphinx", "myst-parser", "sphinx_rtd_theme"]
-
 [project.urls]
 "Homepage" = "https://github.com/davidcellis/ducktools-classbuilder"