diff --git a/src/index.ts b/src/index.ts
index a935c42..9896222 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -21,6 +21,10 @@ export interface IEnumerator<T> {
   toIterator<T>(): Iterator<T>
 }
 
+export interface IArrayEnumerator<T> extends IEnumerator<T> {
+  setIndex(index: number): void
+}
+
 export interface IEnumerable<T> {
   enumerator(): IEnumerator<T>
 }
@@ -224,7 +228,7 @@ function toArrayLikeBuffer<T extends ArrayBufferView>(buffer: T): T & ArrayLike<
 
 type ArrayType<T extends ArrayLike<any> | ArrayBufferView> = T extends ArrayLike<infer U> ? U : T extends ArrayBufferTypes ? number : never
 
-export class ArrayEnumerator<T> implements IEnumerator<T>, Iterator<T>, Iterable<T> {
+export class ArrayEnumerator<T> implements IArrayEnumerator<T>, Iterator<T>, Iterable<T> {
   private _array: ArrayLike<T>
   private _index: number = -1