diff --git a/src/vs/platform/actions/common/menu.ts b/src/vs/platform/actions/common/menu.ts
index 1ca92edef179be1ecbddadcc38f52101abd87464..491968e11cc1ed0fe19cd38d974005c636812af5 100644
--- a/src/vs/platform/actions/common/menu.ts
+++ b/src/vs/platform/actions/common/menu.ts
@@ -21,13 +21,13 @@ export class Menu implements IMenu {
 	private _onDidChange = new Emitter<IMenu>();
 
 	constructor(
-		private id: MenuId,
+		private _id: MenuId,
 		startupSignal: TPromise<boolean>,
 		@ICommandService private _commandService: ICommandService,
 		@IContextKeyService private _contextKeyService: IContextKeyService
 	) {
 		startupSignal.then(_ => {
-			const menuItems = MenuRegistry.getMenuItems(id);
+			const menuItems = MenuRegistry.getMenuItems(_id);
 			const keysFilter = new Set<string>();
 
 			let group: MenuItemGroup;
@@ -48,6 +48,9 @@ export class Menu implements IMenu {
 
 			// subscribe to context changes
 			this._disposables.push(this._contextKeyService.onDidChangeContext(keys => {
+				if (!keys) {
+					throw new Error(`Receiving bad onDidChangeContext-event form MenuId[${this._id.id}]`);
+				}
 				for (let k of keys) {
 					if (keysFilter.has(k)) {
 						this._onDidChange.fire();
diff --git a/src/vs/platform/contextkey/browser/contextKeyService.ts b/src/vs/platform/contextkey/browser/contextKeyService.ts
index 325e8cf9680f41d9448bd1e37ae67449a5eaf736..df96f3c0c0dab414f64c268e211384afcd012949 100644
--- a/src/vs/platform/contextkey/browser/contextKeyService.ts
+++ b/src/vs/platform/contextkey/browser/contextKeyService.ts
@@ -126,7 +126,7 @@ class ContextKey<T> implements IContextKey<T> {
 	}
 }
 
-export abstract class AbstractContextKeyService {
+export abstract class AbstractContextKeyService implements IContextKeyService {
 	public _serviceBrand: any;
 
 	protected _onDidChangeContext: Event<string[]>;
@@ -138,6 +138,8 @@ export abstract class AbstractContextKeyService {
 		this._onDidChangeContextKey = new Emitter<string>();
 	}
 
+	abstract dispose(): void;
+
 	public createKey<T>(key: string, defaultValue: T): IContextKey<T> {
 		return new ContextKey(this, key, defaultValue);
 	}