Rod Stewart's son is all grown up!

On Tuesday, the rock legend, 78, and wife Penny Lancaster, 52, spent the day with son Alastair celebrating his 18th birthday.

A photo from the day shows the couple lounging on the couch with their son. Later, they all get done up as they step out to continue the festivities out on the town.

Stewart and Lancaster also share son Aiden Patrick, 12. The singer is also dad to adult children Renee, 30, Ruby, 35, Sean, 43, and Kimberly, 44.

 Stewart appeared on the cover of the November issue of Haute Living, where he praised his kids and their accomplishments.

“I don’t think I’m as strict with my kids as my mom and dad — especially my dad — were,” Stewart told the outlet. “I’m very lenient with them. None have gotten into any serious trouble. A couple dabbled with drugs, but that’s all done now. I’m very proud of them all.”

He also added that when he’s on the road he misses his family “so much,” and that his loved ones are “a wonderful luxury” when he returns home. 

 According to Haute Living, Stewart already has eight grandchildren.

He celebrated the birth of two new grandchildren earlier this year after his daughter Ruby welcomed her son Otis with partner Jake Kalick on May 9. Meanwhile, Stewart's son Liam welcomed his own son, Louie, with his girlfriend, Nicole, on May 12.