The famous Fleetwood, who was most likely focused on the more pressing issue of facing down the rest of the world's best golfers in the PGA Championship this weekend, seemed about as calm as someone could be about a six-figure banking mistake.
Fleetwood returned the money and it went to the British Open finisher.
A friend of the elder Fleetwood tweeted out an image of the wire transfer from his bank account showing the deposit of the younger Fleetwood's winnings from the British Open played last month at the Carnoustie Golf Links in Scotland.
Careful all you Justin Thomas' out there, you may find some extra change in your bank account...
"This was a clerical error which we are resolving and we apologize for the inconvenience caused to both parties", the European Tour said in a statement.
"I tried to get on their senior tour, so they have my (bank) information", he said.
The American Tommy Fleetwood shared a screenshot showing he had been credited $154,480 by the European Tour.
"At least, he can always say he won $150,000 at the Open".
Fleetwood has four European Tour titles to his name, and finished second at the US Open in June.
Fleetwood - the English one - said: "I didn't know anything about it".
Looks pretty legit to me.
Tommy Fleetwood is no stranger to large checks considering his PGA Tour and European Tour winnings, but Thomas Fleetwood in Clermont, Florida is.
Speaking in St Louis ahead of this week's PGA Championship, world No. 11 Fleetwood said he didn't mind the mistake and saw the amusing side of the mix-up.
"I wouldn't even know if I'd been paid or not because I don't really look". It's a amusing story.