diff --git a/core/spec/helpers/base_helper_spec.rb b/core/spec/helpers/base_helper_spec.rb
index 04013a1da4d..08d27b3d135 100644
--- a/core/spec/helpers/base_helper_spec.rb
+++ b/core/spec/helpers/base_helper_spec.rb
@@ -86,7 +86,7 @@
       expect(html.css(".notice").text).to eq("ok")
       expect(html.css(".foo").text).to be_empty
       expect(html.css(".bar").text).to be_empty
-      expect(helper.output_buffer).to eq("<div class=\"flash notice\">ok</div>")
+      expect(helper.output_buffer.to_s).to eq("<div class=\"flash notice\">ok</div>")
     end
   end