diff --git a/lib/lib.es2015.core.d.ts b/lib/lib.es2015.core.d.ts
index c92a44c2312..c7c7afb821b 100644
--- a/lib/lib.es2015.core.d.ts
+++ b/lib/lib.es2015.core.d.ts
@@ -37,7 +37,7 @@ interface Array<T> {
       * @param thisArg If provided, it will be used as the this value for each invocation of
       * predicate. If it is not provided, undefined is used instead.
       */
-    findIndex(predicate: (value: T, index: number, obj: Array<T>) => boolean, thisArg?: any): number;
+    findIndex(predicate: (value: T) => boolean, thisArg?: any): number;
 
     /**
       * Returns the this object after filling the section identified by start and end with value
diff --git a/lib/lib.es6.d.ts b/lib/lib.es6.d.ts
index a7faa4789a6..8e9de3f4ec9 100644
--- a/lib/lib.es6.d.ts
+++ b/lib/lib.es6.d.ts
@@ -4143,7 +4143,7 @@ interface Array<T> {
       * @param thisArg If provided, it will be used as the this value for each invocation of
       * predicate. If it is not provided, undefined is used instead.
       */
-    findIndex(predicate: (value: T, index: number, obj: Array<T>) => boolean, thisArg?: any): number;
+    findIndex(predicate: (value: T) => boolean, thisArg?: any): number;
 
     /**
       * Returns the this object after filling the section identified by start and end with value