diff --git a/flamenco_worker/worker.py b/flamenco_worker/worker.py
index cb12c015b7ecf28edbf73f38c164a90dc5239e45..90825a9e49cdbf330a3d846fbc335ee8cc95bac9 100644
--- a/flamenco_worker/worker.py
+++ b/flamenco_worker/worker.py
@@ -51,8 +51,8 @@ class WorkerState(enum.Enum):
 
 @attr.s(auto_attribs=True)
 class PreTaskCheckParams:
-    pre_task_check_write: typing.List[str] = []
-    pre_task_check_read: typing.List[str] = []
+    pre_task_check_write: typing.Iterable[str] = []
+    pre_task_check_read: typing.Iterable[str] = []
 
 
 class PreTaskCheckFailed(PermissionError):