diff --git a/extensions/markdown-language-features/src/features/previewConfig.ts b/extensions/markdown-language-features/src/features/previewConfig.ts
index ed09a9ce46eeb1f5f3e65ebb231e72a7a6889b6c..679f3c3ad775cb607982f298defd397fe06f5d38 100644
--- a/extensions/markdown-language-features/src/features/previewConfig.ts
+++ b/extensions/markdown-language-features/src/features/previewConfig.ts
@@ -4,6 +4,7 @@
  *--------------------------------------------------------------------------------------------*/
 
 import * as vscode from 'vscode';
+import { equals } from '../util/arrays';
 
 export class MarkdownPreviewConfiguration {
 	public static getForResource(resource: vscode.Uri) {
@@ -21,7 +22,7 @@ export class MarkdownPreviewConfiguration {
 	public readonly lineHeight: number;
 	public readonly fontSize: number;
 	public readonly fontFamily: string | undefined;
-	public readonly styles: string[];
+	public readonly styles: readonly string[];
 
 	private constructor(resource: vscode.Uri) {
 		const editorConfig = vscode.workspace.getConfiguration('editor', resource);
@@ -49,7 +50,7 @@ export class MarkdownPreviewConfiguration {
 	}
 
 	public isEqualTo(otherConfig: MarkdownPreviewConfiguration) {
-		for (let key in this) {
+		for (const key in this) {
 			if (this.hasOwnProperty(key) && key !== 'styles') {
 				if (this[key] !== otherConfig[key]) {
 					return false;
@@ -57,17 +58,7 @@ export class MarkdownPreviewConfiguration {
 			}
 		}
 
-		// Check styles
-		if (this.styles.length !== otherConfig.styles.length) {
-			return false;
-		}
-		for (let i = 0; i < this.styles.length; ++i) {
-			if (this.styles[i] !== otherConfig.styles[i]) {
-				return false;
-			}
-		}
-
-		return true;
+		return equals(this.styles, otherConfig.styles);
 	}
 
 	[key: string]: any;