diff --git a/tox.ini b/tox.ini
index 06cb9f5657..c8224cad44 100644
--- a/tox.ini
+++ b/tox.ini
@@ -6,7 +6,7 @@ skipsdist = True
 [testenv]
 setenv = VIRTUAL_ENV={envdir}
 usedevelop = True
-install_command = pip install {opts} {packages}
+install_command = pip install -U {opts} {packages}
 deps = -r{toxinidir}/requirements.txt
        -r{toxinidir}/test-requirements.txt
        setuptools_git>=0.4