06/04/2005 AT 07:00 PM EDT
Rod Stewart, who last week announced that he and his fiancee are expecting a child together, has filed for divorce from model Rachel Hunter.
Hunter and the British singer wed in 1990, but split in 1999, court documents show, according to the Associated Press. The paperwork cites irreconcilable differences as the official reason for ending the marriage. The couple have two children together.
Last Wednesday, Stewart, 60, announced that his fiancee Penny Lancaster, 34, is pregnant. "It will come as no surprise that Penny and I wanted to start a family as soon as possible," the Grammy winner told PEOPLE, adding that he is "overjoyed and extremely proud."
The pair, together for nearly six years, say the baby is due December, and afterward they will aim for a spring 2006 wedding. This will be Lancaster’s first child, while Stewart has five children from previous relationships.