Four out of five child car seats in Ireland are incorrectly fitted, according to the Road Safety Authority.
They are running a 'Check it Fits' installation service across the country.
The organisation says that out of more than 35,000 child car seats checked 79% required a major adjustment.
The warning comes as a mother of a three-year-old boy who was allegedly crushed by a car seat has been found guilty of child cruelty in the UK.
Adrian Hoare, 23 allegedly failed to prevent her boyfriend Stephen Waterson, 25, from squashing Alfie Lamb in the footwell of his Audi convertible with his seat in February last year.
Following an Old Bailey that concluded today, a jury was unable to decide whether Waterson was guilty of Alfie’s manslaughter, but found him guilty of intimidation of a witness in the case.