diff --git a/lib/landline/util/multipart.rb b/lib/landline/util/multipart.rb
index 4ed8617..cd8e995 100644
--- a/lib/landline/util/multipart.rb
+++ b/lib/landline/util/multipart.rb
@@ -28,7 +28,7 @@ module Landline
       # Decode charset parameter
       def decode(data)
         data = Landline::Util.unescape_html(data)
-        return data unless self.headers['charset']
+        return data.force_encoding("UTF-8") unless self.headers['charset']
 
         data.force_encoding(self.headers['charset']).encode("UTF-8")
       end