diff --git a/highlightjs/highlightjs.d.ts b/highlightjs/highlightjs.d.ts
index b34d69508..91675cfa6 100644
--- a/highlightjs/highlightjs.d.ts
+++ b/highlightjs/highlightjs.d.ts
@@ -105,7 +105,7 @@ declare module "highlight.js"
 		{
 			className?: string;
 			aliases?: string[];
-			begin: string;
+			begin?: string;
 			end?: string;
 			case_insensitive?: boolean;
 			beginKeyword?: string;