diff --git a/tox.ini b/tox.ini
--- a/tox.ini
+++ b/tox.ini
@@ -19,6 +19,7 @@
 deps =
     mypy >= 0.910
     sqlalchemy-stubs
+    future
 commands =
     # No where close to passing yet, but nice to have.
     - mypy --install-types --non-interactive --junit-xml=junit-{envname}.xml --py2 --ignore-missing-imports lnt