diff --git a/tox.ini b/tox.ini
index 7bb73a8f0..7de820733 100644
--- a/tox.ini
+++ b/tox.ini
@@ -21,6 +21,7 @@ commands =
   rm -rf .testrepository/times.dbm
   bash tools/pretty_tox.sh '{posargs}'
 
+passenv = http_proxy HTTP_PROXY https_proxy HTTPS_PROXY no_proxy NO_PROXY
 
 [testenv:pep8]
 commands =