AceShowbiz -

Pete Wentz of Fall Out Boy will be a father again. The bassist has just announced in an Instagram post that his girlfriend Meagan Camper is pregnant. "We're super excited to announce we're expecting a baby!" he wrote on Monday, February 17. The photo shows the happy couple cuddling and sharing a kiss.

"They've been planning on this for a while. And they're really excited for Bronx to have a new little buddy," a source told PEOPLE. "Meagan is a big sister and has a great relationship with Bronx. She's naturally maternal so this is perfect." The baby will be a second child for Wentz. He is already a father to a 5-year-old son Bronx Mowgli with ex-wife Ashlee Simpson.

During an interview on "The Wendy Williams" show in January, Wentz admitted that he and Camper had been talking about marriage "a lot." Wentz said of his girlfriend, "It's insane that she hangs out with me. I feel like, 'hot girl pictured with homeless man trying to beg her for change' [when we're out together].' This is like charity work here."

The musician, who has been dating the model for three years, continued, "I feel really lucky. It's really interesting when you're in a relationship with somebody who's truly my best friend. I talk to her about everything."