diff --git a/tox.ini b/tox.ini
index 1980668..4814eb5 100644
--- a/tox.ini
+++ b/tox.ini
@@ -6,6 +6,8 @@ extras =
     tests
 deps =
     coverage
+passenv =
+    RUSTUP_HOME
 commands =
     coverage run -m pytest --strict-markers {posargs}
     coverage combine