So it turns out we've been getting overcharged by the Luas this whole time without ever realising it.
Passengers have been wrongly charged peak fares because the clocks on several validation machines were running fast.
Transdev has blamed "clock drift" for the problem, 98fm reports.
"It is possible that PC clock drift can occur due to hardware or software faults or device restarts," they said.
The machines were fixed by technicians yesterday evening.