diff --git a/src/components/Shop/RouteBoard.tsx b/src/components/Shop/RouteBoard.tsx
index 4a0d451a..4a1af874 100644
--- a/src/components/Shop/RouteBoard.tsx
+++ b/src/components/Shop/RouteBoard.tsx
@@ -4090,7 +4090,7 @@ const RouteBoard: React.FC = () => {
     if (oldId === newId) return;
     setDirtyMoves((prev) => {
       const next = new Map(prev);
-      for (const [shopId, laneId] of next) {
+      for (const [shopId, laneId] of Array.from(next.entries())) {
         if (laneId === oldId) next.set(shopId, newId);
       }
       return next;