diff --git a/test/test_stream.rb b/test/test_stream.rb
index 90b7f5af..e8649740 100644
--- a/test/test_stream.rb
+++ b/test/test_stream.rb
@@ -102,7 +102,7 @@ def teardown
 
     def test_with_only_default_entities
       member_value = "<p>#{'A' * @default_entity_expansion_text_limit}</p>"
-      source = StringIO.new(<<-XML)
+      source = <<-XML
 <?xml version="1.0" encoding="UTF-8"?>
 <member>
 #{member_value}