diff --git a/tox.ini b/tox.ini
index 08d266a..a1b9d44 100644
--- a/tox.ini
+++ b/tox.ini
@@ -8,6 +8,7 @@ usedevelop = True
 install_command = pip install -U {opts} {packages}
 setenv =
    VIRTUAL_ENV={envdir}
+passenv = http_proxy HTTP_PROXY https_proxy HTTPS_PROXY no_proxy NO_PROXY
 deps = -r{toxinidir}/requirements.txt
        -r{toxinidir}/test-requirements.txt
 commands = python setup.py testr --slowest --testr-args='{posargs}'