diff --git a/tox.ini b/tox.ini
index b0298fea..dd922c46 100644
--- a/tox.ini
+++ b/tox.ini
@@ -8,7 +8,7 @@ deps =
 setenv =
      PYTHONPATH = .:{envdir}
 commands =
-    py{36,37}: pytest --cov=graphene graphene examples {posargs}
+    py{36,37,38}: pytest --cov=graphene graphene examples {posargs}
 
 [testenv:pre-commit]
 basepython=python3.7