diff --git a/index.js b/index.js
index 34b8f15..91c8c51 100644
--- a/index.js
+++ b/index.js
@@ -7,7 +7,7 @@
     if (str instanceof Buffer) {
       buffer = str;
     } else {
-      buffer = Buffer.from(str.toString(), 'binary');
+      buffer = Buffer.from(String(str), 'binary');
     }
 
     return buffer.toString('base64');