diff --git a/hydrogen/converter/handlers/converter.py b/hydrogen/converter/handlers/converter.py
index f67e163..920f80b 100644
--- a/hydrogen/converter/handlers/converter.py
+++ b/hydrogen/converter/handlers/converter.py
@@ -12,10 +12,10 @@
 
 
 def base_padding(data, length=4):
+    data = utf8(data)
     if len(data) % length != 0:
-        data = '%s%s' % (data, '=' * (length - len(data) % length))
+        data = data + b'=' * (length - len(data) % length)
 
-    data = utf8(data)
     return data