Caching does not seem to work with only Cache-Control header

I have a server that sends data that always expires at midnight of the same day it was requested.

Cache-Control: max-age=30187

However, sending a GET request to the server one minute after midnight still fetches the result from the cache instead of issuing a new request to the server. The server does not send an ETag response header. Might that be the problem and confuse the IE caching?

I am using XHR to perform the requests. Clearing the IE cache manually fetches the page after midnight (naturally).