What actions must I take if my broker made an error and took too small of a RMD from my IRA?

When I worked with my broker to take my RMD they made an error and processed too small of an RMD by $2,850. I have a letter from the broker acknowledging this fact. The added the $ 2,850 on January 31, 2019. Do I report the correct amount for 2018 taxes? Are there other forms I need to complete? Can I get a waiver of the additional excise tax that would normally be charged? If so, what is the process?