diff --git a/tox.ini b/tox.ini
index de73c395f359132062ead816de42fe671cf7d0d9..0bf16c4cf7921f83f8571137c48506b03358e49e 100644
--- a/tox.ini
+++ b/tox.ini
@@ -2,7 +2,7 @@
 exclude = obsolete,.tox
 
 [testenv]
-passenv = XDG_CACHE_HOME USE_COMPOSE
+passenv = XDG_CACHE_HOME,USE_COMPOSE
 deps =
     coverage
     flake8