Over the 1989 Christmas holiday period it was reported that part of Grianán an Aileach had collapsed. An inspection of the site was carried out on 4 January 1990 by an architect and an archaeologist employed by the Commissioners of Public Works. They reported that the collapse occurred outwards on the south-west side of the fort along a four to six metre stretch. The lower part of the wall, up to 1.2 metres high, remained sound.
The area of the collapse was fenced off immediately and a danger notice erected. Works commenced on rebuilding the wall on 8 January 1990 and are progressing satisfactorily. The high winds in February held up the works but they are due for completion by the end of March.