diff --git a/tox.ini b/tox.ini
index 89bcad806532..463e26bf9128 100644
--- a/tox.ini
+++ b/tox.ini
@@ -18,7 +18,7 @@ deps = -r{toxinidir}/test-requirements.txt
 commands =
   find . -type f -name "*.pyc" -delete
   bash tools/pretty_tox.sh '{posargs}'
-passenv = http_proxy HTTP_PROXY https_proxy HTTPS_PROXY no_proxy NO_PROXY
+passenv = http_proxy HTTP_PROXY https_proxy HTTPS_PROXY no_proxy NO_PROXY OS_DEBUG
 # there is also secret magic in pretty_tox.sh which lets you run in a fail only
 # mode. To do this define the TRACE_FAILONLY environmental variable.