diff --git a/tox.ini b/tox.ini
index 76c1f1ebd47e..e3438e287278 100644
--- a/tox.ini
+++ b/tox.ini
@@ -2,6 +2,7 @@
 envlist = py26,py27,pep8
 
 [testenv]
+setenv = VIRTUAL_ENV={envdir}
 deps = -r{toxinidir}/tools/pip-requires
        -r{toxinidir}/tools/test-requires
 commands = /bin/bash run_tests.sh -N -P