Motorists have been left bemused by a temporary road sign advising them: "When light is cock, wait here".
The sign was placed on Afan Valley Road in Neath, where work by Wales and West Utilities was being carried out.
The sign read "pan fo'r golau'n goc, arhoswch yma" (when light is cock, wait here") instead of "pan fo'r golau'n goch, arhoswch yma" (when light is red, wait here).
The work has now been concluded and the sign has been removed.
Welsh speaker Alun Saunders, from Cimla, came across the sign on Wednesday, June 24.
"It’s a sorry - yet, slightly funny - example of such a typo. The important things are that those making signs (and errors) realise and make it right - thanks to social media both Neath Port Talbot Council and Wales and West Utilities have already responded apologetically and with humility," the 40-year-old said.
"It’s also vital that our minoritised national language - my first language - isn’t considered ‘lesser’ or that speakers of either language get constantly pitted against each other. We’re one Wales."
Another local Welsh speaker, who does not want to be named, said: "It doesn't offend me but it shows a lack of care because there have been so many times that this has happened on Welsh signs around the country and you never see mistakes on English ones which speaks volumes."
On Twitter, a Neath Port Talbot Council spokesman wrote: "We'll admit we've made some mistakes in the past on signage but this one was not our 'goch-up'.
"We have informed Wales and West Utilities."
Wales and West Utilities work management and street works manager, Graham Bond, said: “We are aware of an unfortunate spelling mistake on a traffic light sign at one of our work sites on Afan Valley Road in Neath. The work in the area is complete and the sign has been removed.
“We’re sorry for any offence caused and are working with our contractors to make sure this does not happen again.”
