diff --git a/tox.ini b/tox.ini
index feb680246..d1b02463b 100644
--- a/tox.ini
+++ b/tox.ini
@@ -16,7 +16,7 @@ commands =
 # remove bash & pipe & grep hack after cryptography ships with openssl 1.1.0
 whitelist_externals = bash
 commands =
-  bash -c 'py.test --cov netlib --cov mitmproxy --cov pathod --color=yes --timeout 60 test/netlib test/mitmproxy/script test/pathod/test_utils.py test/pathod/test_log.py test/pathod/test_language_generators.py test/pathod/test_language_writer.py test/pathod/test_language_base.py test/pathod/test_language_http.py test/pathod/test_language_websocket.py test/pathod/test_language_http2.py 2>&1 | grep -v Cryptography_locking_cb'
+  bash -c 'set -o pipefail ; py.test --cov netlib --cov mitmproxy --cov pathod --color=yes --timeout 60 test/netlib test/mitmproxy/script test/pathod/test_utils.py test/pathod/test_log.py test/pathod/test_language_generators.py test/pathod/test_language_writer.py test/pathod/test_language_base.py test/pathod/test_language_http.py test/pathod/test_language_websocket.py test/pathod/test_language_http2.py 2>&1 | grep -v Cryptography_locking_cb'
   codecov -e TOXENV
 
 [testenv:docs]