Here's how we know that Katy Perry is going to love this newest video version of 'ROAR' -- because it's impossible not to!

The patients and staff at Children's Hospital at Dartmouth-Hitchcock -- CHaD for short -- lip-sync to Katy's inspiring hit in a viral video that has amassed more than a half million views since it was uploaded Monday (Oct. 21).

Katy's song about triumphing over the odds almost seems as if it were written for the New Hampshire hospital's initiative to showcase its efforts. The clip shows the kids acting out the song as best they can, surrounded by cheerful staff members. The results are nothing short of heartwarming, and the world has responded in kind.

"The CHaD kids have heard your 'ROAR,' and the buzz has rubbed off on them," the hospital writes on its Facebook page. "The excited smiles in the hospital have been contagious and BEAUTIFUL to see. This video brought a sense of power to these children who are faced with illness, but aren't giving up."

Those so moved are invited to donate to CHaD here.