diff --git a/actionpack/test/fixtures/ruby_template.ruby b/actionpack/test/fixtures/ruby_template.ruby
index 5097bce47c0..3e0bc445a2b 100644
--- a/actionpack/test/fixtures/ruby_template.ruby
+++ b/actionpack/test/fixtures/ruby_template.ruby
@@ -1,2 +1,2 @@
-body = ""
+body = +""
 body << ["Hello", "from", "Ruby", "code"].join(" ")