James Potten from Bristol, U.K. said that he was surprised when he recently opened a FedEx delivery to find out that instead of his new Amazon Kindle, he received a package that noted “patient tumor – specimen enclosed.”

“When I opened it I had quite a shock,” he said in an interview with the BBC.

The package was supposed to got to the Royal Free Hospital in London. In a statement, the hospital said it was aware that the package “intended for one of its institutions… was delivered to an address in Bristol,” according to the publication.

Wow @FedEx. You've swapped my new kindle with a tumor specimen. Still waiting for collection #FedExFail #notmykindle pic.twitter.com/GlleuOYbiE

— James Potten (@jamespotten) January 9, 2016

FedEx, meanwhile, said it “regretted the error.”

“My name was on the outside, but the contents weren’t what I expected,” added Potten in the interview. “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.”