Arnold Schwarzenegger hasn’t used his Twitter account in over a month but he logged on Monday to show support for his son Christopher, who was injured in a boogie-boarding accident the weekend of July 15.

“Thanks for all your support for Christopher. It means a lot to me & to him,” Arnold wrote.

“He’s doing much better & we’ll have him back at full speed soon.”

Christopher, 13, reportedly suffered a collapsed lung, broken bones and broken ribs while out in the ocean, which occurred while he was with his mother, Maria Shriver – who made the dramatic 911 call after the accident.

Arnold’s tweet came on the same day his lawyer filed a revised version of his Response to Maria’s divorce petition.

Arnold’s original Response – a document required under California divorce law – requested that that court not award Maria spousal support or attorney fees.

The revised document reversed course on both those issues.

Arnold’s tweet follows in the footsteps of his other children who have also posted notes of support for their brother.

“Thank you guys for ur concern and prayers for my baby brother! He’s a tough little guy and getting better!” Katherine wrote. “Please keep praying for him! Xo”

“Thank you everyone for your messages about my brother,” Patrick tweeted. “This kid is strongest kid I ever seen. Keep praying.”

Arnold and Maria have both been seen making frequent visits to the hospital for Christopher.