diff --git a/src/util/collection/AsyncCollection.ts b/src/util/collection/AsyncCollection.ts
index c6901fd..aa29c85 100644
--- a/src/util/collection/AsyncCollection.ts
+++ b/src/util/collection/AsyncCollection.ts
@@ -330,7 +330,7 @@ export class AsyncCollection<T> {
         await this.each(async (item, index) => {
             const result = await func(item, index)
             if ( typeof result !== 'undefined' ) {
-                newItems.push(result as NonNullable<T2>)
+                newItems.push(result as unknown as NonNullable<T2>)
             }
         })