diff --git a/tox.ini b/tox.ini
index c98a8d9..9968728 100644
--- a/tox.ini
+++ b/tox.ini
@@ -6,6 +6,7 @@ skipsdist = True
 [testenv]
 usedevelop = True
 setenv = VIRTUAL_ENV={envdir}
+passenv = http_proxy HTTP_PROXY https_proxy HTTPS_PROXY no_proxy NO_PROXY
 install_command = pip install -U {opts} {packages}
 deps = -r{toxinidir}/requirements.txt
 commands = python setup.py testr --slowest --testr-args='{posargs}'