diff --git a/tox.ini b/tox.ini
index ba2e43b..69d01e6 100644
--- a/tox.ini
+++ b/tox.ini
@@ -25,7 +25,7 @@ deps =
     wheel
 commands =
     python setup.py -qq bdist_wheel
-    pip install --pre --find-links ./dist/ flake8
+    pip install -U --pre --find-links ./dist/ flake8
     flake8 --version
     flake8 src/flake8/ tests/ setup.py