diff --git a/test/ruby/test_io_m17n.rb b/test/ruby/test_io_m17n.rb
index 57943df25f..ba8d8f00a9 100644
--- a/test/ruby/test_io_m17n.rb
+++ b/test/ruby/test_io_m17n.rb
@@ -1473,6 +1473,10 @@ EOT
       content = File.read("iso-2022-jp.txt", :mode=>"rb:ascii-8bit")
       assert_equal("\"&<>"'丂\e$B$\"\e(B\n\"".force_encoding("ascii-8bit"), content)
 
+      open("utf-16be.txt", "wb:utf-16be", xml: :attr) {|f| f.print '&<>"\''; f.puts "\u4E02\u3042" }
+      content = File.read("utf-16be.txt", :mode=>"rb:ascii-8bit")
+      assert_equal("\0\"\0&\0a\0m\0p\0;\0&\0l\0t\0;\0&\0g\0t\0;\0&\0q\0u\0o\0t\0;\0'\x4E\x02\x30\x42\0\n\0\"".force_encoding("ascii-8bit"), content)
+
       open("eucjp.txt", "w:euc-jp:utf-8", xml: :attr) {|f|
         f.print "\u4E02" # U+4E02 is 0x3021 in JIS X 0212
       }