diff --git a/tox.ini b/tox.ini
index 800557efb6ed..140f4ce4f94e 100644
--- a/tox.ini
+++ b/tox.ini
@@ -17,6 +17,9 @@ setenv = VIRTUAL_ENV={envdir}
          OS_STDOUT_CAPTURE=1
          OS_STDERR_CAPTURE=1
          OS_TEST_TIMEOUT=160
+         # NOTE(efried): This is only effective in tox versions after 3.0.0rc1
+         # https://github.com/tox-dev/tox/commit/336f4f6bd8b53223f940fc5cfc43b1bbd78d4699
+         PYTHONDONTWRITEBYTECODE=1
 deps = -r{toxinidir}/test-requirements.txt
 commands =
   find . -type f -name "*.pyc" -delete