"This is a whole new level of cute."
That's how an astute YouTuber described this adorable video of a 6-year-old boy cradling his baby brother in his arms and singing him a lullaby.
"Best big brother ever!" declared another netizen after watching the clip.
The video, which was first uploaded in December, has experienced a viral resurgence this week after being shared by a number of news outlets. As of Tuesday afternoon, it had been viewed more than 600,000 times.
Watch the video above and prepare for super-cuteness.