diff --git a/src/vs/workbench/api/node/extHostDocumentSaveParticipant.ts b/src/vs/workbench/api/node/extHostDocumentSaveParticipant.ts
index 2cd38a8dff8..08bd121dabe 100644
--- a/src/vs/workbench/api/node/extHostDocumentSaveParticipant.ts
+++ b/src/vs/workbench/api/node/extHostDocumentSaveParticipant.ts
@@ -18,13 +18,6 @@ import { ExtHostDocuments } from 'vs/workbench/api/node/extHostDocuments';
 import { SaveReason } from 'vs/workbench/services/textfile/common/textfiles';
 import * as vscode from 'vscode';
 
-declare class WeakMap<K, V> {
-	// delete(key: K): boolean;
-	get(key: K): V;
-	// has(key: K): boolean;
-	set(key: K, value?: V): WeakMap<K, V>;
-}
-
 export class ExtHostDocumentSaveParticipant extends ExtHostDocumentSaveParticipantShape {
 
 	private _documents: ExtHostDocuments;
@@ -168,4 +161,4 @@ export class ExtHostDocumentSaveParticipant extends ExtHostDocumentSaveParticipa
 			return TPromise.wrapError(new Error('concurrent_edits'));
 		});
 	}
-}
\ No newline at end of file
+}
diff --git a/src/vs/workbench/api/node/mainThreadHeapService.ts b/src/vs/workbench/api/node/mainThreadHeapService.ts
index d19a269a945..235556d3be3 100644
--- a/src/vs/workbench/api/node/mainThreadHeapService.ts
+++ b/src/vs/workbench/api/node/mainThreadHeapService.ts
@@ -12,17 +12,6 @@ import { consumeSignals, GCSignal } from 'gc-signals';
 import { createDecorator } from 'vs/platform/instantiation/common/instantiation';
 import { registerSingleton } from 'vs/platform/instantiation/common/extensions';
 
-
-declare class WeakMap<K, V> {
-	set(key: K, value?: V): WeakMap<K, V>;
-}
-
-declare class Set<E> {
-	add(e: E): this;
-	has(e: E): boolean;
-	delete(e: E): boolean;
-}
-
 export const IHeapService = createDecorator<IHeapService>('heapService');
 
 export interface IHeapService {