diff --git a/src/lib/es2015.collection.d.ts b/src/lib/es2015.collection.d.ts
index 521dd29be9f..a3207175c48 100644
--- a/src/lib/es2015.collection.d.ts
+++ b/src/lib/es2015.collection.d.ts
@@ -4,7 +4,7 @@ interface Map<K, V> {
     forEach(callbackfn: (value: V, index: K, map: Map<K, V>) => void, thisArg?: any): void;
     get(key: K): V | undefined;
     has(key: K): boolean;
-    set(key: K, value?: V): Map<K, V>;
+    set(key: K, value?: V): this;
     readonly size: number;
 }
 
@@ -20,8 +20,7 @@ interface WeakMap<K, V> {
     delete(key: K): boolean;
     get(key: K): V | undefined;
     has(key: K): boolean;
-    set(key: K, value?: V): WeakMap<K, V>;
-
+    set(key: K, value?: V): this;
 }
 
 interface WeakMapConstructor {
@@ -32,7 +31,7 @@ interface WeakMapConstructor {
 declare var WeakMap: WeakMapConstructor;
 
 interface Set<T> {
-    add(value: T): Set<T>;
+    add(value: T): this;
     clear(): void;
     delete(value: T): boolean;
     forEach(callbackfn: (value: T, index: T, set: Set<T>) => void, thisArg?: any): void;
@@ -48,11 +47,10 @@ interface SetConstructor {
 declare var Set: SetConstructor;
 
 interface WeakSet<T> {
-    add(value: T): WeakSet<T>;
+    add(value: T): this;
     clear(): void;
     delete(value: T): boolean;
     has(value: T): boolean;
-
 }
 
 interface WeakSetConstructor {