diff --git a/src/index.d.ts b/src/index.d.ts
index 1ba2cb8..2331f59 100644
--- a/src/index.d.ts
+++ b/src/index.d.ts
@@ -2131,6 +2131,11 @@ export declare namespace TelegramWebApps {
      * validity.
      */
     readonly hash: string
+    /**
+     * A signature of all passed parameters (except hash), which the third party can
+     * use to check their validity.
+     */
+    readonly signature: string
   }
 
   /**