diff -urp '--exclude=*~' marc-1.0.4.orig/lib/marc/reader.rb marc-1.0.4/lib/marc/reader.rb
--- marc-1.0.4.orig/lib/marc/reader.rb	2021-01-30 20:51:28.746261429 +0900
+++ marc-1.0.4/lib/marc/reader.rb	2021-01-30 21:07:12.367242406 +0900
@@ -443,7 +443,7 @@ module MARC
         # get an exception from inside ruby-marc, and it may change
         # in future implementations. 
         if params[:internal_encoding]
-          str = str.encode(params[:internal_encoding], params)
+          str = str.encode(params[:internal_encoding], **params)
         elsif (params[:invalid] || params[:replace] || (params[:validate_encoding] == true))
 
           if params[:validate_encoding] == true && ! str.valid_encoding?