diff --git a/.eslintrc.js b/.eslintrc.js
index 8da9c8a6f..d19389b3d 100644
--- a/.eslintrc.js
+++ b/.eslintrc.js
@@ -3,14 +3,14 @@ module.exports = {
   env: {
     browser: true,
     commonjs: true,
-    es6: true,
+    es2020: true,
   },
   extends: "eslint:recommended",
   parserOptions: {
     ecmaFeatures: {
       jsx: true,
     },
-    ecmaVersion: 2018,
+    ecmaVersion: 2015,
     sourceType: "module",
   },
   plugins: ["react", "@typescript-eslint"],
diff --git a/src/index.d.ts b/src/index.d.ts
index bd0a39ba6..3cf706bac 100644
--- a/src/index.d.ts
+++ b/src/index.d.ts
@@ -1,3 +1,4 @@
+import BN from "bn.js"
 import { BatchExchangeViewer } from "../build/types/BatchExchangeViewer"
 
 export { BatchExchange } from "../build/types/BatchExchange"