diff --git a/lib/core.js b/lib/core.js
index 22f74a51b56..3dad5d2454d 100644
--- a/lib/core.js
+++ b/lib/core.js
@@ -35,7 +35,9 @@ declare class Object {
     static create(o: any, properties?: any): any; // compiler magic
     static defineProperties(o: any, properties: any): any;
     static defineProperty(o: any, p: any, attributes: any): any;
-    static entries(object: any): Array<[string, mixed]>;
+    static entries <T> (o: { +[s: string]: T }) : Array<[string, T]>;
+    static entries <T> (o: Array<T> | $ReadOnlyArray<T>) : Array<[string, T]>;
+    static entries (o: any) : Array<[string, mixed]>;
     static freeze<T>(o: T): T;
     static getOwnPropertyDescriptor(o: any, p: any): any;
     static getOwnPropertyNames(o: any): Array<string>;
@@ -45,11 +47,14 @@ declare class Object {
     static isExtensible(o: any): boolean;
     static isFrozen(o: any): boolean;
     static isSealed(o: any): boolean;
+    static keys <T> (o: { +[key: T]: any }): Array<T>;
     static keys(o: any): Array<string>;
     static preventExtensions(o: any): any;
     static seal(o: any): any;
     static setPrototypeOf(o: any, proto: ?Object): bool;
-    static values(object: any): Array<mixed>;
+    static values <T> (o: { +[s: string]: T }) : Array<T>;
+    static values <T> (o: Array<T> | $ReadOnlyArray<T>) : Array<T>;
+    static values(o: any): Array<mixed>;
     hasOwnProperty(prop: any): boolean;
     isPrototypeOf(o: any): boolean;
     propertyIsEnumerable(prop: any): boolean;