Los Angeles, Dec 21 (IANS): Hollywood actress Demi Moore will soon be a grandmother. The 'Charlie's Angels' actress' daughter, Rumer Willis, is expecting her first baby with boyfriend Derek Richard Thomas, the couple revealed in a joint Instagram post.

Already playing the role of proud grandmother, Moore shared their announcement post on her own Instagram, reports 'People' magazine. "Entering my hot kooky unhinged grandma era," Moore (60), wrote alongside the couple's photos.

"So happy for you my love!" she later added in the comments. Emma Heming Willis, who is married to Rumer's father Bruce Willis, also shared her excitement for the mom-to-be.

"Baby news is happy news!!! Congratulations @rumerwillis and @derekrichardthomas We are elated over here," she wrote on Instagram.

According to 'People', Rumer and Thomas made the special announcement with a carousel of bump photos. In the first snap, the father-to-be wrapped his hand around her growing belly and gave it a sweet kiss while Rumer smiled.

She also showed off her pregnant silhouette as she stood near a window in another image. A photo that featured a very excited Thomas rounded out the set of pictures.

The 'What Lies Ahead' actress and her musician/producer beau have been romantically linked since earlier this year. The baby will be the first grandchild for Rumer's parents- Bruce (67) and Moore.