diff --git a/test/test_helper.rb b/test/test_helper.rb
index 7db8811ed..8cbd3c2f9 100644
--- a/test/test_helper.rb
+++ b/test/test_helper.rb
@@ -71,7 +71,7 @@ def assert_equivalent_xml(expected, actual)
       Diffy::Diff.new(
         sort_attributes(expected_xml.root).to_xml(indent: 2),
         sort_attributes(actual_xml.root).to_xml(indent: 2)
-      ).to_formatted_s(:color)
+      ).to_s(:color)
     }
   end