diff --git a/marked/marked-tests.ts b/marked/marked-tests.ts
index 4e4f5fcaa9..bbf30accd0 100644
--- a/marked/marked-tests.ts
+++ b/marked/marked-tests.ts
@@ -36,4 +36,9 @@ console.log(marked.parse('i am using __markdown__.', options, callback));
 
 var text = 'something';
 var tokens = marked.lexer(text, options);
-console.log(marked.parser(tokens));
\ No newline at end of file
+console.log(marked.parser(tokens));
+
+var renderer = new marked.Renderer();
+renderer.heading = function(text, level, raw) {
+    return text + level.toString() + raw;
+};
diff --git a/marked/marked.d.ts b/marked/marked.d.ts
index 80fa04709c..63dad27b30 100644
--- a/marked/marked.d.ts
+++ b/marked/marked.d.ts
@@ -73,7 +73,7 @@ interface MarkedRenderer {
     code(code: string, language: string): string;
     blockquote(quote: string): string;
     html(html: string): string;
-    heading(text: string, level: number): string;
+    heading(text: string, level: number, raw: string): string;
     hr(): string;
     list(body: string, ordered: boolean): string;
     listitem(text: string): string;