Bruce Boxleitner and Melissa Gilbert
Graham Whitby Boot-Allstar/Globe
08/25/2011 AT 07:10 PM EDT
Nearly six months after announcing their separation
, Melissa Gilbert filed for divorce from her husband of 16 years, Bruce Boxleitner.
Gilbert, 47, cites irreconcilable differences in her filing Monday in Los Angeles Superior Court. She seeks joint custody of their son Michael, 15, who was named after Gilbert's costar and mentor Michael Landon on TV's Little House on the Prairie.
Gilbert also seeks not to pay spousal support to Boxleitner, 61, an actor who recently appeared in Tron: Legacy.
The pair also have three adult sons from their previous marriages.
The divorce papers were filed the same week that Gilbert's sister, The Talk
's Sara Gilbert, announced the end of her relationship
with Allison Adler. They will share custody of their two children.