diff --git a/perl/README b/perl/README
index 224ff08c..ae924ee6 100644
--- a/perl/README
+++ b/perl/README
@@ -102,6 +102,11 @@ TODO
         "while(read($socket, $buffer, $arbitrary_buffer_size)) { ... }"). We
         should implement the internal buffer for the unpacker.
 
+    UTF8 mode
+        Data::MessagePack::Unpacker supports utf8 mode, which decodes
+        strings as UTF8-8. << Data::MessagePack->unpack >> should support
+        utf8 mode in a future.
+
 AUTHORS
     Tokuhiro Matsuno