Credit: Instagram

You know what they say: The sisters that work out together, show off their toned butts together. (That's a saying, right?) Judging by a new photo, this appears to be Kim Kardashian and Kendall Jenner's motto.

There's no denying that Kim has a bangin' post-baby body following giving birth to cutie North West, which Kim says is the result of long workouts at the gym. And now Kim's proving just how much she's been pumping iron.

On January 10, Kim snapped a selfie in which she shows off her backside at the gym. But Kim appears to have been joined by an unexpected partner in the booty-centric pic.

"Barging in on Kim's booty selfie," Kendall captions the photo on Instagram in which she appears to be photobombing Kim's selfie. Too booties are better than one, right?

It's very cute that Kim and Kendall appear to be workout buddies. All that working out is clearly paying off, since their bodies look amaze! And we love their cute exercise attire, with those sexy stretch pants and Kendall's cute headband. 

This is hardly the first time in the new year that Kim has posted a pic of her smokin' hot behind. Last weekend, Kim and pal Blac Chyna showed off their butts in a photo of their bathroom mirror.

Are you impressed that Kim and Kendall spend so much time in the gym?

Source: Kendall on Instagram