diff --git a/src/render.ts b/src/render.ts
index db11d23..a91b2d6 100644
--- a/src/render.ts
+++ b/src/render.ts
@@ -30,6 +30,8 @@ export async function render_markdown_to_html(markdown: string, options: Markdow
 		async: true,
 		breaks: options.breaks || false,
 		renderer: create_renderer(options),
+		mangle: false,
+		headerIds: false,
 	};
 
 	marked.use({
diff --git a/src/renderer.ts b/src/renderer.ts
index ffbe77e..0042f05 100644
--- a/src/renderer.ts
+++ b/src/renderer.ts
@@ -28,13 +28,8 @@ export function create_renderer(opts: MarkdownOptions) {
 }
 
 function heading(renderer: marked.Renderer, opts: MarkdownOptions) {
-	return function(orig_text: string, level: 1 | 2 | 3 | 4 | 5 | 6, raw: string, slugger) {
+	return function(orig_text: string, level: 1 | 2 | 3 | 4 | 5 | 6, raw: string) {
 		let { text, id, html_attrs } = parse_attributes(raw);
-	
-		if (! id) {
-			id = slugger.slug(text);
-			html_attrs.push(`id="${id}"`);
-		}
 		
 		return `
 <h${level} ${html_attrs.join(' ')}>