The Alarm frontman Mike Peters has added his weight to a boy's campaign to find a lifesaver for his father.
Peter McCleave's son, Max, wrote a letter that went viral trying to find a blood stem cell match for his father who has myeloma, a blood cancer.
More than 20,000 joined a donor register after Max's letter was published and now the family want more.
They are joining the singer, who was moved by Max's letter, and music fans at an event at Bethesda on Saturday.
Max wrote: "If my daddy doesn't find a stem cell match he will only have seven more years with me and I want lots more."
Mr McCleave, 41, from Bunbury, Cheshire, who was diagnosed two years after initially suffering from pneumonia, has had several rounds of chemotherapy but he still needs to find a matching blood stem cell donor to survive.
Along with sons Max, eight, and Seb, five, and wife Jenn, he will be "living life to the full, having fun and making memories together" while taking part in the Snowdonia Rocks 20km walk and ZipRoc music festival on Saturday.
"But at the forefront of mine and my children's minds will be that we need to find that lifesaving match if we want to enjoy many more father's day weekends together," he said.
The festival was set up by Mike Peters and his wife, Jules, who have both had cancer, after they started a charity to encourage people to register as bone marrow donors.
He said: "There are currently still 2,000 people in the UK who, like Peter, are still waiting for that lifesaving donor to appear. And they won't appear if we don't shout about getting on the list."