A stream emptying into the River Brora, just to the north of the head of Loch Brora, Allt a' Mhuilinn rises as headwaters on the western slopes of Cnoc a' Chrubaich Mhoir. It flows west and then south for a distance of 5 miles (8 km). It is joined by the Allt Ach a' Bhathaich at Ascoile.