diff --git a/.github/workflows/python-checks.yml b/.github/workflows/python-checks.yml
index 2af4ba2..203137d 100644
--- a/.github/workflows/python-checks.yml
+++ b/.github/workflows/python-checks.yml
@@ -15,7 +15,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        python-version: ["3.9", "3.10", "3.11", "3.12"]
+        python-version: ["3.10", "3.11", "3.12"]
 
     steps:
     - uses: actions/checkout@v4
@@ -29,7 +29,6 @@ jobs:
         python -m pip install --upgrade pip wheel
         pip install -e .[test]
     - name: Type check with mypy
-      if: ${{ matrix.python-version != 3.9 }}
       run: |
         mypy
     - name: Test with pytest
diff --git a/README.md b/README.md
index 25f5781..d3d818f 100644
--- a/README.md
+++ b/README.md
@@ -31,7 +31,7 @@ Australasian Computing Education Conference (ACE '24).  DOI:
 Install
 -------
 
-Requires Python 3.9 or higher.
+Requires Python 3.10 or higher.
 
 1. Create and activate a Python virtual environment.
    (E.g., `python3 -m venv venv; source venv/bin/activate`)
diff --git a/pyproject.toml b/pyproject.toml
index 14f2cb8..7e2f7b3 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -10,7 +10,7 @@ authors = [
     { name='Mark Liffiton', email='liffiton@gmail.com' }
 ]
 readme = 'README.md'
-requires-python = '>=3.9'
+requires-python = '>=3.10'
 
 classifiers = [
     "Development Status :: 4 - Beta",
@@ -54,16 +54,13 @@ log_level = 'DEBUG'
 testpaths = 'tests'
 addopts = [
     "--import-mode=importlib",
-    "-n8",
+    "-n 8",
 ]
 markers = [
     "use_real_openai: marks any test that sends requests to the real OpenAI endpoint",
 ]
 
 
-[tool.ruff]
-target-version = "py310"  # let ruff operate w/ 3.10+ assumptions (mostly for type annotation changes in 3.10)
-
 [tool.ruff.lint]
 select = ["ALL"]
 ignore = [