diff --git a/src/List.tsx b/src/List.tsx
index d71db85c..9b6d892b 100644
--- a/src/List.tsx
+++ b/src/List.tsx
@@ -134,7 +134,7 @@ export function RawList<T>(props: ListProps<T>, ref: React.Ref<ListRef>) {
       if (typeof itemKey === 'function') {
         return itemKey(item);
       }
-      return item?.[itemKey];
+      return item?.[itemKey as string];
     },
     [itemKey],
   );
diff --git a/src/utils/CacheMap.ts b/src/utils/CacheMap.ts
index 5de321ba..a428bbb4 100644
--- a/src/utils/CacheMap.ts
+++ b/src/utils/CacheMap.ts
@@ -13,12 +13,12 @@ class CacheMap {
   }
 
   set(key: React.Key, value: number) {
-    this.maps[key] = value;
+    this.maps[key as string] = value;
     this.id += 1;
   }
 
   get(key: React.Key) {
-    return this.maps[key];
+    return this.maps[key as string];
   }
 }