diff --git a/tox.ini b/tox.ini
index babf033..bcacef3 100644
--- a/tox.ini
+++ b/tox.ini
@@ -7,7 +7,11 @@ toxworkdir={env:TOXWORKDIR_BASE:}{toxinidir}/.tox
 # useful for tests to know they are running under ci
 # respect user's cache dirs to prevent tox from crapping into project dir
 [testenv]
-passenv = CI,CI_*,MYPY_CACHE_DIR,PYTHONPYCACHEPREFIX
+passenv =
+    CI
+    CI_*
+    MYPY_CACHE_DIR
+    PYTHONPYCACHEPREFIX
 
 
 # just the very core tests with minimal dependencies