diff --git a/tox.ini b/tox.ini
index c826d09a..9ac61b98 100644
--- a/tox.ini
+++ b/tox.ini
@@ -5,6 +5,7 @@ envlist = py34,py27,pep8
 [testenv]
 deps = -r{toxinidir}/test-requirements.txt
 commands = python setup.py testr --slowest --testr-args='{posargs}'
+passenv = http_proxy HTTP_PROXY https_proxy HTTPS_PROXY no_proxy NO_PROXY
 
 [testenv:pep8]
 commands = flake8