diff --git a/tox.ini b/tox.ini
index da03c5f..e2da5f8 100644
--- a/tox.ini
+++ b/tox.ini
@@ -2,6 +2,8 @@
 envlist = py26,py27,py32,py33,style,docs
 
 [testenv]
+# tox passes --pre to pip by default, but we don't want that
+install_command = pip install {opts} {packages}
 distribute = False
 commands = nosetests -d --with-coverage --cover-inclusive --cover-package stevedore []
 deps =