diff --git a/cylc/flow/workflow_files.py b/cylc/flow/workflow_files.py
index a4e009630b..add79adbbd 100644
--- a/cylc/flow/workflow_files.py
+++ b/cylc/flow/workflow_files.py
@@ -25,7 +25,7 @@
 from contextlib import suppress
 from enum import Enum
 import errno
-from queue import deque
+from collections import deque
 import os
 from pathlib import Path
 import re