diff --git a/tox.ini b/tox.ini
index 6350146c..004cf98d 100644
--- a/tox.ini
+++ b/tox.ini
@@ -3,7 +3,7 @@ minversion = 2.0
 envlist = py35,py27,pypy,pep8
 
 [testenv]
-install_command = pip install -U {opts} {packages}
+install_command = pip install {opts} {packages}
 whitelist_externals = find
                       rm
 deps =