There’s a signal blind people give if they need assistance. Here’s how to lend a hand (when asked).

A TikTok video has gone viral for showing a way to help blind people that most people don’t know.

The video was made by Jemma Brown of England who has a blind mother with a guide dog named Vivvy. She filmed the video as a response to a series of questions she was asked on Twitter.

“How would you approach someone with a cane?” a viewer asked. “I wouldn’t want to scare someone by coming out of nowhere if that makes sense,” Jemma replied.

“Cc: How to tell if someone with a guide dog needs help,” the viewer asked. “Easy, the owner lets go of the handle and places it on the dogs back,” Jemma answered.

In Jemma’s video, her mother walks down the street until she reaches the curb and then drops the handle on the dog’s back while picking up a leash. “Would you like some help?” Jemma asks.

She added that if the person says yes then the bystander should say, “Cool, would you like to take my arm. I’ll come ’round the other side round the dog.”

The video makes note of the fact that Jemma grabs her mother’s elbow on the opposite side of the dog so that it isn’t startled.

It’s really that simple. But for those of us who want to help, and for those of us who sometimes need help, it makes all the difference.