diff --git a/tox.ini b/tox.ini
index cb5decfcf..0fcf23e86 100644
--- a/tox.ini
+++ b/tox.ini
@@ -19,6 +19,7 @@ whitelist_externals = sh
 commands =
   find . -type f -name "*.pyc" -delete
   sh tools/pretty_tox.sh '{posargs}'
+passenv = http_proxy HTTP_PROXY https_proxy HTTPS_PROXY no_proxy NO_PROXY
 
 [testenv:docs]
 commands = python setup.py build_sphinx -E