diff --git a/tox.ini b/tox.ini
index e60b2e0..5d0a55f 100644
--- a/tox.ini
+++ b/tox.ini
@@ -9,9 +9,11 @@ toxworkdir={env:TOXWORKDIR_BASE:}{toxinidir}/.tox
 [testenv]
 passenv = 
 # useful for tests to know they are running under ci
-  CI CI_*
+  CI
+  CI_*
 # respect user's cache dirs to prevent tox from crapping into project dir
-  MYPY_CACHE_DIR PYTHONPYCACHEPREFIX
+  MYPY_CACHE_DIR
+  PYTHONPYCACHEPREFIX
 
 [testenv:tests]
 commands =