diff --git a/extensions/markdown-language-features/src/features/preview.ts b/extensions/markdown-language-features/src/features/preview.ts
index 4c0d0911296..4ecef4ac7b6 100644
--- a/extensions/markdown-language-features/src/features/preview.ts
+++ b/extensions/markdown-language-features/src/features/preview.ts
@@ -8,7 +8,7 @@ import * as path from 'path';
 
 import { Logger } from '../logger';
 import { MarkdownContentProvider } from './previewContentProvider';
-import { disposeAll } from '../util/dispose';
+import { Disposable } from '../util/dispose';
 
 import * as nls from 'vscode-nls';
 import { getVisibleLine, MarkdownFileTopmostLineMonitor } from '../util/topmostLineMonitor';
@@ -60,7 +60,7 @@ interface PreviewStyleLoadErrorMessage extends WebviewMessage {
 	};
 }
 
-export class MarkdownPreview {
+export class MarkdownPreview extends Disposable {
 
 	public static viewType = 'markdown.preview';
 
@@ -70,7 +70,6 @@ export class MarkdownPreview {
 	private readonly editor: vscode.WebviewPanel;
 	private throttleTimer: any;
 	private line: number | undefined = undefined;
-	private readonly disposables: vscode.Disposable[] = [];
 	private firstUpdate = true;
 	private currentVersion?: { resource: vscode.Uri, version: number };
 	private forceUpdate = false;
@@ -149,17 +148,18 @@ export class MarkdownPreview {
 		topmostLineMonitor: MarkdownFileTopmostLineMonitor,
 		private readonly _contributionProvider: MarkdownContributionProvider,
 	) {
+		super();
 		this._resource = resource;
 		this._locked = locked;
 		this.editor = webview;
 
 		this.editor.onDidDispose(() => {
 			this.dispose();
-		}, null, this.disposables);
+		}, null, this._disposables);
 
 		this.editor.onDidChangeViewState(e => {
 			this._onDidChangeViewStateEmitter.fire(e);
-		}, null, this.disposables);
+		}, null, this._disposables);
 
 		this.editor.webview.onDidReceiveMessage((e: CacheImageSizesMessage | RevealLineMessage | DidClickMessage | ClickLinkMessage | ShowPreviewSecuritySelectorMessage | PreviewStyleLoadErrorMessage) => {
 			if (e.source !== this._resource.toString()) {
@@ -191,19 +191,19 @@ export class MarkdownPreview {
 					vscode.window.showWarningMessage(localize('onPreviewStyleLoadError', "Could not load 'markdown.styles': {0}", e.body.unloadedStyles.join(', ')));
 					break;
 			}
-		}, null, this.disposables);
+		}, null, this._disposables);
 
 		vscode.workspace.onDidChangeTextDocument(event => {
 			if (this.isPreviewOf(event.document.uri)) {
 				this.refresh();
 			}
-		}, null, this.disposables);
+		}, null, this._disposables);
 
 		topmostLineMonitor.onDidChangeTopmostLine(event => {
 			if (this.isPreviewOf(event.resource)) {
 				this.updateForView(event.resource, event.line);
 			}
-		}, null, this.disposables);
+		}, null, this._disposables);
 
 		vscode.window.onDidChangeTextEditorSelection(event => {
 			if (this.isPreviewOf(event.textEditor.document.uri)) {
@@ -213,13 +213,13 @@ export class MarkdownPreview {
 					source: this.resource.toString()
 				});
 			}
-		}, null, this.disposables);
+		}, null, this._disposables);
 
 		vscode.window.onDidChangeActiveTextEditor(editor => {
 			if (editor && isMarkdownFile(editor.document) && !this._locked) {
 				this.update(editor.document.uri);
 			}
-		}, null, this.disposables);
+		}, null, this._disposables);
 	}
 
 	private readonly _onDisposeEmitter = new vscode.EventEmitter<void>();
@@ -242,18 +242,17 @@ export class MarkdownPreview {
 	}
 
 	public dispose() {
+		super.dispose();
 		if (this._disposed) {
 			return;
 		}
 
 		this._disposed = true;
 		this._onDisposeEmitter.fire();
-
 		this._onDisposeEmitter.dispose();
+
 		this._onDidChangeViewStateEmitter.dispose();
 		this.editor.dispose();
-
-		disposeAll(this.disposables);
 	}
 
 	public update(resource: vscode.Uri) {
diff --git a/extensions/markdown-language-features/src/features/workspaceSymbolProvider.ts b/extensions/markdown-language-features/src/features/workspaceSymbolProvider.ts
index 12e51c75d76..73e04269fce 100644
--- a/extensions/markdown-language-features/src/features/workspaceSymbolProvider.ts
+++ b/extensions/markdown-language-features/src/features/workspaceSymbolProvider.ts
@@ -4,7 +4,7 @@
  *--------------------------------------------------------------------------------------------*/
 
 import * as vscode from 'vscode';
-import { disposeAll } from '../util/dispose';
+import { Disposable } from '../util/dispose';
 import { isMarkdownFile } from '../util/file';
 import { Lazy, lazy } from '../util/lazy';
 import MDDocumentSymbolProvider from './documentSymbolProvider';
@@ -18,25 +18,13 @@ export interface WorkspaceMarkdownDocumentProvider {
 	readonly onDidDeleteMarkdownDocument: vscode.Event<vscode.Uri>;
 }
 
-class VSCodeWorkspaceMarkdownDocumentProvider implements WorkspaceMarkdownDocumentProvider {
+class VSCodeWorkspaceMarkdownDocumentProvider extends Disposable implements WorkspaceMarkdownDocumentProvider {
 
-	private readonly _onDidChangeMarkdownDocumentEmitter = new vscode.EventEmitter<SkinnyTextDocument>();
-	private readonly _onDidCreateMarkdownDocumentEmitter = new vscode.EventEmitter<SkinnyTextDocument>();
-	private readonly _onDidDeleteMarkdownDocumentEmitter = new vscode.EventEmitter<vscode.Uri>();
+	private readonly _onDidChangeMarkdownDocumentEmitter = this._register(new vscode.EventEmitter<SkinnyTextDocument>());
+	private readonly _onDidCreateMarkdownDocumentEmitter = this._register(new vscode.EventEmitter<SkinnyTextDocument>());
+	private readonly _onDidDeleteMarkdownDocumentEmitter = this._register(new vscode.EventEmitter<vscode.Uri>());
 
 	private _watcher: vscode.FileSystemWatcher | undefined;
-	private _disposables: vscode.Disposable[] = [];
-
-	public dispose() {
-		this._onDidChangeMarkdownDocumentEmitter.dispose();
-		this._onDidDeleteMarkdownDocumentEmitter.dispose();
-
-		if (this._watcher) {
-			this._watcher.dispose();
-		}
-
-		disposeAll(this._disposables);
-	}
 
 	async getAllMarkdownDocuments() {
 		const resources = await vscode.workspace.findFiles('**/*.md', '**/node_modules/**');
@@ -64,7 +52,7 @@ class VSCodeWorkspaceMarkdownDocumentProvider implements WorkspaceMarkdownDocume
 			return;
 		}
 
-		this._watcher = vscode.workspace.createFileSystemWatcher('**/*.md');
+		this._watcher = this._register(vscode.workspace.createFileSystemWatcher('**/*.md'));
 
 		this._watcher.onDidChange(async resource => {
 			const document = await this.getMarkdownDocument(resource);
@@ -98,15 +86,16 @@ class VSCodeWorkspaceMarkdownDocumentProvider implements WorkspaceMarkdownDocume
 }
 
 
-export default class MarkdownWorkspaceSymbolProvider implements vscode.WorkspaceSymbolProvider {
+export default class MarkdownWorkspaceSymbolProvider extends Disposable implements vscode.WorkspaceSymbolProvider {
 	private _symbolCache = new Map<string, Lazy<Thenable<vscode.SymbolInformation[]>>>();
 	private _symbolCachePopulated: boolean = false;
-	private _disposables: vscode.Disposable[] = [];
 
 	public constructor(
 		private _symbolProvider: MDDocumentSymbolProvider,
 		private _workspaceMarkdownDocumentProvider: WorkspaceMarkdownDocumentProvider = new VSCodeWorkspaceMarkdownDocumentProvider()
-	) { }
+	) {
+		super();
+	}
 
 	public async provideWorkspaceSymbols(query: string): Promise<vscode.SymbolInformation[]> {
 		if (!this._symbolCachePopulated) {
@@ -130,10 +119,6 @@ export default class MarkdownWorkspaceSymbolProvider implements vscode.Workspace
 		}
 	}
 
-	public dispose(): void {
-		disposeAll(this._disposables);
-	}
-
 	private getSymbols(document: SkinnyTextDocument): Lazy<Thenable<vscode.SymbolInformation[]>> {
 		return lazy(async () => {
 			return this._symbolProvider.provideDocumentSymbolInformation(document);
diff --git a/extensions/markdown-language-features/src/util/dispose.ts b/extensions/markdown-language-features/src/util/dispose.ts
index 19b3b3f4f19..548094c28e5 100644
--- a/extensions/markdown-language-features/src/util/dispose.ts
+++ b/extensions/markdown-language-features/src/util/dispose.ts
@@ -14,3 +14,29 @@ export function disposeAll(disposables: vscode.Disposable[]) {
 	}
 }
 
+export abstract class Disposable {
+	private _isDisposed = false;
+
+	protected _disposables: vscode.Disposable[] = [];
+
+	public dispose(): any {
+		if (this._isDisposed) {
+			return;
+		}
+		this._isDisposed = true;
+		disposeAll(this._disposables);
+	}
+
+	protected _register<T extends vscode.Disposable>(value: T): T {
+		if (this._isDisposed) {
+			value.dispose();
+		} else {
+			this._disposables.push(value);
+		}
+		return value;
+	}
+
+	protected get isDisposed() {
+		return this._isDisposed;
+	}
+}
\ No newline at end of file