diff --git a/types/String.d.ts b/types/String.d.ts
index 1ea0c5a..ff10d2a 100644
--- a/types/String.d.ts
+++ b/types/String.d.ts
@@ -13,4 +13,6 @@ interface String extends Iterable<string> {
 
 	/** The current number of characters in the string. */
 	size(this: string): number;
+
+	readonly [n: number]: string;
 }