diff --git a/.gitignore b/.gitignore
index bcbae80..2a246a8 100644
--- a/.gitignore
+++ b/.gitignore
@@ -10,5 +10,6 @@
 
 /*.egg-info
 /virtualenv
+/venv
 
 config.yaml
diff --git a/requirements.txt b/requirements.txt
index ac1d18f..7742d8f 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -12,3 +12,4 @@ pytz >=2011k
 httplib2
 lxml
 pytest
+tox
diff --git a/tox.ini b/tox.ini
index 93fde38..e4a30e5 100644
--- a/tox.ini
+++ b/tox.ini
@@ -3,5 +3,7 @@ envlist = py
 
 [testenv]
 deps = -rrequirements.txt
-passenv = S3TEST_CONF S3_USE_SIGV4
+passenv =
+  S3TEST_CONF
+  S3_USE_SIGV4
 commands = pytest {posargs}