Don't operate on the safebuffer, operate on a string and convert.

actionpack/lib/action_view/helpers/text_helper.rb

@@ -258,11 +258,12 @@ module ActionView
         text = ''.html_safe if text.nil?
         start_tag = tag('p', html_options, true)
         text = sanitize(text) unless options[:sanitize] == false
+        text = text.to_str
         text.gsub!(/\r\n?/, "\n")                    # \r\n and \r -> \n
         text.gsub!(/\n\n+/, "</p>\n\n#{start_tag}")  # 2+ newline  -> paragraph
         text.gsub!(/([^\n]\n)(?=[^\n])/, '\1<br />') # 1 newline   -> br
         text.insert 0, start_tag
-        text.html_safe.safe_concat("</p>")
+        text = ActiveSupport::SafeBuffer.new(text).safe_concat("</p>")
       end
 
       # Creates a Cycle object whose _to_s_ method cycles through elements of an