diff --git a/tox.ini b/tox.ini
index d5f401a7a..519020f98 100644
--- a/tox.ini
+++ b/tox.ini
@@ -13,7 +13,6 @@ deps=
     typing
 setenv =
     SPHINX_TEST_TEMPDIR = {envdir}/testbuild
-    PYTHONDONTWRITEBYTECODE = true
 commands=
     {envpython} -Wall tests/run.py --ignore tests/py35 --cov=sphinx \
         --durations 25 {posargs}