seconds_until_end_of_day expires for Cache in Rails

A colleague of mine had to cache some html until the end of the day but found it difficult because cache expects expires_in which is relative. We cant pass an absolute Time.now :P

So we now have seconds_until_end_of_day in 4.0.2, but we use Rails 3 :(

But patching Time is simple

def seconds_until_end_of_day
  end_of_day.to_i - to_i
end

http://apidock.com/rails/v4.0.2/Time/seconds_until_end_of_day