Westboro Baptist Church leader Fred Phelps died at the age of 84, the BBC reports, but that didn't stop some on Twitter from confusing him for 28-year-old Michael Phelps, subsequently mourning him instead.
Fred was a controversial figure, as the BBC explains, for his church's views on homosexuality and the military.
By contrast, Michael is the most successful Olympian in history, with 18 gold medals to his name.
An easy thing to mix up? Apparently so.
At one stage, "RIP Michael Phelps" was trending on Twitter, as noted by Chris Kaltenbach of The Baltimore Sun, and a sampling of the messages tells their own story:
Phelps is, we should stress, alive and well.
[H/T Huffington Post]