You need to add this to the response headers, either in specific actions
@response.headers["Content-Type"] = "text/html;
Or in a before filter that you apply to as many actions as you want:
class FooController < ApplicationController
@response.headers["Content-Type"] = "text/html; charset=koi8-r"
Note that Rails built in Action Cache will break your code if you use it
Rails will send the default charset for cached requests, and Page
may not work either.