Rob Kardashian: "I can't wait to hear what my baby's voice sounds like"

Rob Kardashian says he "can't wait" for Dream to say her first word.

The 30-year-old voiced his excitement for the 4-month-old's milestones Wednesday on Twitter and re-posted new photos Blac Chyna shared of their daughter.

"I can't wait to hear what my baby's voice sounds like ... lol ... I'm waiting," he tweeted to his 6.9 million followers.

The "Keeping Up with the Kardashians" star later compiled a collage of screenshots from clips Blac Chyna shared of Dream on Snapchat.

The photos show the infant cooing in a "Dessert First" bib.

"GOODnight my pretty baby," he captioned the post on Instagram.

Kardashian and Blac Chyna reportedly split again in February after a highly-publicized breakup in December.

Blac Chyna said in the April issue of Cosmopolitan South Africa that she's "in it for the long haul" with her ex-fiance.

"I feel like every person who's in a long-term relationship, or who is committed to their person, goes through ups and downs. Everything isn't always going to be peaches and cream. If it is, then it's fake. I'm in it for the long haul," she told the magazine.

"I feel like everything isn't going to be perfect, but I know we love each other and we're fighting for each other, and the people we surround ourselves with are rooting for us. It makes everything so much easier," the star added.

Kardashian and Blac Chyna welcomed Dream in November after getting engaged in April after three months of dating.

Sources told People this month that Kardashian's mom, Kris Jenner, will support the star if he battles Blac Chyna for custody.