diff --git a/web/src/store/v1/memo.ts b/web/src/store/v1/memo.ts
index 752c7a25..5d1fe2fe 100644
--- a/web/src/store/v1/memo.ts
+++ b/web/src/store/v1/memo.ts
@@ -17,7 +17,7 @@ export const useMemoStore = create(
     getState: () => get(),
     fetchMemos: async (request: Partial<ListMemosRequest>) => {
       const { memos, nextPageToken } = await memoServiceClient.listMemos(request);
-      const memoMap = get().memoMapByName;
+      const memoMap = { ...get().memoMapByName };
       for (const memo of memos) {
         memoMap[memo.name] = memo;
       }