diff --git a/tox.ini b/tox.ini
index 0e156d63b..865ef5383 100644
--- a/tox.ini
+++ b/tox.ini
@@ -21,6 +21,7 @@ deps =
     # Extras
     botocore>=1.4.87
 passenv =
+    CC
     S3_TEST_FILE_URI
     AWS_ACCESS_KEY_ID
     AWS_SECRET_ACCESS_KEY