upgrade iphone 4 before buying new phone?

I am planning on replacing my iPhone 4 (iOS 5) with an iPhone 5C (yes, I'm that broke & Radio Shack is doing $100 trade-ins).

Do I need to upgrade my 4 to iOS 7 before backing up? That is to say, would an iOS 7 phone have trouble restoring from an iOS 5 backup?

Never mind found the answer five minutes after I posted this. And yes I did a search first. Just took two times to find the answer.