James Potten was excited to receive his new Amazon Kindle in the mail, but when the package arrived at his home in the United Kingdom, it wasn’t what he expected.

Inside the package was a human tumor, which the BBC reports was supposed to go to the Royal Free Hospital in London, but ended up on Potten's doorstep.

"When I opened it I had quite a shock," he said told the BBC.

Potten said he was contacted Thursday by FedEx which said it tried to deliver the package, but he wasn’t home. He called the delivery service back and the driver returned with the package containing the tumor.

"I haven't opened the sealed box, which says exempt patient tissue, as it doesn't belong to me. The tracking code on the item had the same first five and last three numbers as my order, but it wasn't my Kindle,” he said according to the BBC. "I've been trying to get FedEx to collect it as it is potentially a sample that needs to be tested and sent back with some urgency. I don't know where my Kindle is, but if it is at the Royal Free I'd be happy to do an exchange."

Potten told The Sun that he contacted FedEx to tell it about the mix-up multiple times, but the company insisted that the package he received was his Kindle.

BBC reports FedEx finally accepted the mix-up, saying it “regretted the error” and “will consider future changes to our processes.” The report added that the company would be retrieving his package on Sunday to “deliver to the correct address.”

Read more at BBC and The Sun.