diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
index 9df18f99..6635a35b 100644
--- a/.github/workflows/tests.yml
+++ b/.github/workflows/tests.yml
@@ -30,7 +30,7 @@ jobs:
           - {name: '3.9', python: '3.9', os: ubuntu-latest, tox: py39}
           - {name: '3.8', python: '3.8', os: ubuntu-latest, tox: py38}
           - {name: '3.7', python: '3.7', os: ubuntu-latest, tox: py37}
-          - {name: '3.6', python: '3.6', os: ubuntu-latest, tox: py36}
+          - {name: '3.6', python: '3.6', os: ubuntu-20.04, tox: py36}
     steps:
       - uses: actions/checkout@v3
       - uses: actions/setup-python@v4