Nova Scotia, Canada - Anyone who has seen 15-year-old Mackenzie knows the cat has a grumpy pout. But a visit with Santa Claus this Christmas turned "Grumpy Mack's" frown upside down.

"She has resting grumpy face," Mackenzie's owner Angela Rasuse told The Dodo.

"She can be the happiest cat in the world – like, thriving and having the best time, and she just has this grumpy look on her face."

McKenzie has been a bit sour since she was adopted in 2019 from Angela's grandparents.

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But one thing she loves? Her harness and leash.

"It was the weirdest thing in the world," Angela recalled. "Here’s this grumpy, murdery cat, but the second you put a harness on her, she becomes an adventure cat."

The videos of Angela and her "grumpy adventure cat" have racked up millions of views on TikTok.

Another one of the few things Grumpy Mack apparently loves? Santa Claus!

When Angela brought her grumpy cat to the local pet store to meet Santa this year, she experienced a whole new side of her little kitty.

The Pet Valu in Nova Scotia, Canada hosted a fundraiser for a local food bank, where pets could take pictures with Santa in return for their owners' donation of a nonperishable food item.

At first, Angela wasn't sure how her fussy companion would react to meeting the man in red – but after McKenzie sat on Santa's lap, she didn't want to leave!

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"She trotted in like she owned the place and waited in line with all the other dogs," Angela said.

"I put her beside Santa and she growled, because she didn’t know what was going on. But then she played with the ball on Santa’s hat."

As their visit continued, she even purred and wagged her tail!

But the cuteness didn't stop there. When it came time to let the next animal have its turn, the cat began to protest.

"She hissed at me when I tried to take her away from Santa," the owner laughed. "She absolutely loved Santa."

The cat was definitely feline the magic of Christmas!