The One Direction singer has been left upset after his stepfather Mark's mother passed away earlier this week.
Confirming the sad news, Mark wrote on Twitter: "The birds are singing today. Rest in Peace my beautiful Mum. I'm going to really miss you."
The cause of Margaret's death has not been disclosed.
Her husband Keith also sent out tributes, tweeting: "There was never one day in 47 years of being married to me that Mrs T didn't tell me she loved me."
He added in a later message yesterday (04.01.14): "So much love from you for Mrs T. You have been so kind to me today. I thank you all from the bottom of my breaking heart."
Keith and Margaret have been grandparents to Louis, 22, almost his entire life after his mother, Johannah married Mark when he was still a toddler.
Louis has yet to make comment on his loss, but he is very close to his grandparents on both sides of his family, featuring them in the video to the band's song 'Story of My Life'.