diff --git a/youtube_dl/postprocessor/xattrpp.py b/youtube_dl/postprocessor/xattrpp.py
index 1cb8ecf1c..4317ba836 100644
--- a/youtube_dl/postprocessor/xattrpp.py
+++ b/youtube_dl/postprocessor/xattrpp.py
@@ -99,7 +99,7 @@ class XAttrMetadataPP(PostProcessor):
                     if infoname == "upload_date":
                         value = hyphenate_date(value)
 
-                    byte_value = value.encode(preferredencoding())
+                    byte_value = value.encode('utf-8')
                     write_xattr(filename, xattrname, byte_value)
 
             return True, info