How to make an iPhone 4 case fit an iPhone 5?

I got a iphone 4/4s case and i need it to fit my 5.

You return it and get an iPhone 5 case
the iPhone 5 is SIGNIFICANTLY larger than the iPhone 4

Scissors and glue.

That's obviously not going to happen. The iPhone 5 is taller than the 4 & slimmer as well.

Is the case made of silly putty? You can stretch it if so.

Get a saw and trim the iphone 5 down to 3.5"inches instead of 4"…

You have two choices:
1. Return it and get an iPhone 5 case.
2. Cut off the top of the case and lose 50% of the protection (and 100% of the value).