I got my refund approved and sent to me, but I need to amend my return. Should I cash out my check from IRS or should I wait for an amended tax return?

IRS approved my tax return and sent me a check. I need to amend my tax return as I forgot to include form 1099-R in my tax return. Should I cash out the check that I have received from IRS or should I file an amended tax return and wait for another check to come later after my amended tax return is processed?

Thanks