An Algonquin Park portrait locked away and forgotten for years has pulled in a small fortune.

The piece named Sketch for Lake in Algonquin Park was painted by famed Canadian artist Tom Thomson and was recently discovered by an Edmonton woman in her basement. CBC News reports Glenna Gardiner had always been told by her grandfather the painting was a Tom Thomson original, but she never believed him. After recently coming across the painting and having it assessed by an art expert, Gardiner found her grandfather had been telling the truth, it was Thomson’s work.

The portrait was auctioned off in Toronto on Wednesday and netted Gardiner over $480,000. Thomson was known to often use Algonquin Park as inspiration for his art and his body was discovered in the park in 1917.