diff --git a/.github/workflows/lint.yml b/.github/workflows/lint.yml
index 230e92ad..a137a617 100644
--- a/.github/workflows/lint.yml
+++ b/.github/workflows/lint.yml
@@ -8,10 +8,10 @@ jobs:
 
     steps:
     - uses: actions/checkout@v2
-    - name: Set up Python 3.7
+    - name: Set up Python 3.9
       uses: actions/setup-python@v2
       with:
-        python-version: 3.7
+        python-version: 3.9
     - name: Install dependencies
       run: |
         python -m pip install --upgrade pip
diff --git a/tox.ini b/tox.ini
index 3ddfbabb..4e1cc9dc 100644
--- a/tox.ini
+++ b/tox.ini
@@ -32,6 +32,7 @@ commands =
 [testenv:mypy]
 deps =
     mypy
+    types-six
 commands =
     mypy graphene