diff --git a/plugins/poll/spec/controllers/posts_controller_spec.rb b/plugins/poll/spec/controllers/posts_controller_spec.rb
index 868116716d6..e0eea906037 100644
--- a/plugins/poll/spec/controllers/posts_controller_spec.rb
+++ b/plugins/poll/spec/controllers/posts_controller_spec.rb
@@ -83,7 +83,7 @@ describe PostsController do
     end
 
     it "should have at most 'SiteSetting.poll_maximum_options' options" do
-      raw = "[poll]\n"
+      raw = +"[poll]\n"
       (SiteSetting.poll_maximum_options + 1).times { |n| raw << "\n- #{n}" }
       raw << "\n[/poll]"