diff --git a/test/ruby/test_transcode.rb b/test/ruby/test_transcode.rb
index 0bb6b8085f..b61d3d39db 100644
--- a/test/ruby/test_transcode.rb
+++ b/test/ruby/test_transcode.rb
@@ -36,6 +36,7 @@ class TestTranscode < Test::Unit::TestCase
     assert_equal("\u3042".encode, "\xA4\xA2".force_encoding('EUC-JP'))
     assert_equal("\xE3\x81\x82\x81".force_encoding("utf-8").encode,
                  "\xA4\xA2?".force_encoding('EUC-JP'))
+    Encoding.default_internal = default_default_internal
   end
 
   def test_length