diff --git a/typescript/core/base.ts b/typescript/core/base.ts
index 6182a0833..4d6550f4f 100644
--- a/typescript/core/base.ts
+++ b/typescript/core/base.ts
@@ -38,7 +38,9 @@ export interface _base {
 
     size: (collection: any) => number;
 
-    each: <T>(collection: T[] | object | string, callback?: ((index: number, value: T) => void) | object | string, thisArg?: any) => any;
+    each<T>(collection: ArrayLike<T>, iteratee?: (index: number, value: T) => void, thisArg?: any): ArrayLike<T>;
+    each<T extends object, K extends keyof T>(collection: T, iteratee?: (index: K, value: T[K]) => void, thisArg?: any): T;
+    each<T>(collection: T, iteratee?: any, thisArg?: any): T;
 
     map: <T, U>(collection: T[] | object | string | null | undefined, callback?: ((index: number, value: T) => U) | object | string, thisArg?: any) => U[];