RSpec2 error codes testing

I have an issue with testing error codes. If a record is not found, it
raises exception ActiveRecord::RecordNotFound. The thing is, I wanna
check if 404 is returned. If I go ahead and just check :

response.status.should == 404

Then this will make the test case fail as RecordNotFound exception is
thrown and not caught. If I go ahead and say

expect {}.to

and then check for the status code, then it will fail again, as this
catches the exception and the response code is 200.

How should I test if 404 is returned in this kind of case ?