When Sydney Brownell was stuck at work late one night, her nearly 2-year-old son, Wallace, did what most toddlers will do when missing their mom.

He began saying 'Mama' and looking for her to come through the door, according to his dad, Mike Brownell, who watched it all unfold.

"I could tell he was really missing her," he said.

Brownell, a Chicago-based copywriter for an ad agency, thought he could turn his son's words into a song to distract him. When Wallace played along perfectly, the duo's song became a YouTube sensation.

Brownell, who says he has been singing to Wallace "since he was first put into my arms," started strumming chords on his guitar to the words that Wallace was repeating over and over, "Mama, I love you."

As Wallace began to sing along, Brownell captured the moment on his phone so he could send it to Sydney at work.

"We both work late hours sometimes and text each other when there's no end in sight," Brownell said. "I made up that song with just the words he was saying and he started singing along so I thought I'd capture it and send it over to Sydney."

Brownell's idea was a hit with Sydney who, according to her husband, "shed tears of joy."

"She also laughed because there's just that scene where he jumps up into the camera and just starts saying, 'Hi,'" he said of his camera-friendly son.

Brownell says Wallace was asleep when Sydney got home late that November night, but the family of three continues to sing the song together.

As the Brownells watched the video in the days after, they got such a laugh over it that they posted it to YouTube, where it has been viewed over 7,000 times.

"It's less surprising only because it's my child," Brownell joked of the video's popularity.

In the month since the video was filmed, Brownell reports that Wallace has expanded his song repertoire to include another member of the family, their dog, Bogger.

"He'll sing, 'Bogger, I love you,'" Brownell said.