If you have a layout in your Camping app, like this:

  def layout
    xhtml_strict do
      # awesome stuff here
    end
  end

it will not render with a DOCTYPE, even though it’s supposed to. The solution is to wrap it in a capture block:

  def layout
    capture do
      xhtml_strict do
        # awesome standards-compliant stuff here
      end
    end
  end

This is a -Markaby– Camping bug.