diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index bea404b..6d7f5f6 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -10,12 +10,6 @@ jobs:
       - uses: actions/setup-python@v1
         with:
           python-version: "3.6"
-      - uses: actions/setup-python@v1
-        with:
-          python-version: "3.7"
-      - uses: actions/setup-python@v1
-        with:
-          python-version: "3.8"
       - uses: actions/setup-python@v1
         with:
           python-version: "3.9"
diff --git a/tox.ini b/tox.ini
index c08fe8b..2c57287 100644
--- a/tox.ini
+++ b/tox.ini
@@ -1,6 +1,7 @@
 [tox]
-# When adding a new Python version here, please also update the list of Python versions called by the GitHub Actions workflow (.github/workflows/ci.yml).
-envlist = py{36,37,38,39},flake8,mypy,package
+# When updating the Python versions here,
+# please also update the corresponding Python versions in the GitHub Actions workflow (.github/workflows/ci.yml).
+envlist = py{36,39},flake8,mypy,package
 
 [testenv]
 commands = python -m unittest discover --start-directory ./tests