finding out gender

We have our 20 week scan this Friday, and my husband is adamant we won't find out. I used to think I'd like a surprise, but now I really want to know what we're having!! We can't agree, and I know if I force it he'll say yes to finding out, but I don't want to ruin the surprise for him. There's no way I can find out and keep it to myself...! Anyone have any advice on this issue?! It would be appreciated :)