diff --git a/src/utils/to-base64.js b/src/utils/to-base64.js
index fdc3ab4..a6b78a4 100644
--- a/src/utils/to-base64.js
+++ b/src/utils/to-base64.js
@@ -6,7 +6,7 @@ function toBase64(str) {
     if (typeof Buffer !== 'undefined') {
         return Buffer.from(str).toString('base64')
     } else {
-        return btoa(str)
+        return btoa(String.fromCharCode(...new TextEncoder().encode((str))))
     }
 }