diff --git a/src/lib/es2015.collection.d.ts b/src/lib/es2015.collection.d.ts
index 4cdb2d187a5..6a2c43cd050 100644
--- a/src/lib/es2015.collection.d.ts
+++ b/src/lib/es2015.collection.d.ts
@@ -16,12 +16,10 @@ interface MapConstructor {
 declare var Map: MapConstructor;
 
 interface ReadonlyMap<K, V> {
-  forEach(
-      callbackfn: (value: V, key: K, map: ReadonlyMap<K, V>) => void,
-      thisArg?: any): void;
-  get(key: K): V|undefined;
-  has(key: K): boolean;
-  readonly size: number;
+    forEach(callbackfn: (value: V, key: K, map: ReadonlyMap<K, V>) => void, thisArg?: any): void;
+    get(key: K): V|undefined;
+    has(key: K): boolean;
+    readonly size: number;
 }
 
 interface WeakMap<K, V> {
@@ -55,10 +53,9 @@ interface SetConstructor {
 declare var Set: SetConstructor;
 
 interface ReadonlySet<T> {
-  forEach(callbackfn: (value: T, value2: T, set: ReadonlySet<T>) => void, thisArg?: any):
-      void;
-  has(value: T): boolean;
-  readonly size: number;
+    forEach(callbackfn: (value: T, value2: T, set: ReadonlySet<T>) => void, thisArg?: any): void;
+    has(value: T): boolean;
+    readonly size: number;
 }
 
 interface WeakSet<T> {