diff --git a/tox.ini b/tox.ini
index 3218dde..f6ed14a 100644
--- a/tox.ini
+++ b/tox.ini
@@ -24,4 +24,8 @@ deps =
 commands = {env:_PYTEST_CMD:pytest} {env:_PYTEST_MORE_ARGS:} {posargs:-vvl}
 
 [testenv:mypy]
+skip_install = true
+allowlist_externals = poetry
+commands_pre =
+    poetry install --with=dev
 commands = mypy