Demi Moore helped ring in Bruce Willis’ 78th birthday on Sunday, one month after his dementia diagnosis.

The “St. Elmo’s Fire” star filmed herself and her family members singing “Happy Birthday” to the actor over the weekend.

Willis, who was noticeably missing a tooth, sang along before dramatically blowing out candles.

His wife, Emma Heming, sweetly kissed his cheek.

“Happy birthday, BW!” Moore, 60, captioned the Instagram footage. “So glad we could celebrate you today. Love you and love our family.”

She concluded, “Thank you to everyone for the love and warm wishes. We all feel them.”

The former couple were married from 1987 to 2000 and share three adult children.

Rumer Willis, Scout Willis and Tallulah Willis were present at Willis’ birthday celebration, as well as his and Heming’s younger daughters, Evelyn and Mabel.

In her own touching post, Heming, 44, called Willis “pure love.”

The model gushed, “He is so loved. And I’ll be loving him always. Happy Birthday my sweet ????.”

Heming went on to share her “sadness,” telling her followers that she “started the morning by crying.”

She concluded, “I do have times of sadness every day, grief every day, and I’m really feeling it today on his birthday.”

Heming and the rest of Willis’ family members announced in February that the Golden Globe winner had been diagnosed with frontotemporal dementia.

“FTD is a cruel disease,” they wrote in a joint statement last month. “Today there are no treatments for the disease, a reality that we hope can change in the years ahead.”

Since revealing Willis’ diagnosis, Heming has pleaded with paparazzi to give him “space” in multiple Instagram videos.

“Please don’t be yelling at my husband, asking how he’s doing, whatever,” she requested after the Emmy winner was hounded on a coffee trip.

“The woo-hooing and the yippee-ki-yay’s — just don’t do it. … Allow for our family or whoever’s with him that day to be able to get him from Point A to Point B safely.”