diff --git a/tox.ini b/tox.ini
index 38d9b21..9ce5dfa 100644
--- a/tox.ini
+++ b/tox.ini
@@ -19,7 +19,8 @@ conda_install_args=
     --override-channels
 
 # Pass through the following environment variables which may be needed for the CI
-; passenv = HOME WINDIR LC_ALL LC_CTYPE CI TRAVIS
+# (maybe only needed for MacOS?)
+passenv = HOME WINDIR LC_ALL LC_CTYPE CI TRAVIS
 
 # Running the tests from within the tests/ dir avoids importing from source tree
 changedir = tests