Kendall Jenner is ''scared'' about her sister Kylie turning 18.

The 'Keeping Up With The Kardashians' star reaches the milestone on Monday (10.08.15) and her 19-year-old sibling appears to be worried about what antics she'll get up to.

She wrote on Instagram: ''Weekend vibes #KyliesTurning18ImScared. (sic)''

Meanwhile, it was previously revealed that Kylie will be paid over $100,000 to celebrate her own birthday at the Beachclub Montreal in Canada.

The club owner Olivier Primeau is said to have also organised for the 17-year-old beauty to be wined and dined on a luxury boat just off the island, before being treated to a $3,000 birthday cake.

And Kylie previously admitted she was looking forward to going out for the first time ''legally'' without a chaperone.

She said: ''What the first thing I want to do is maybe have like a birthday party and then maybe go on a trip with just my friends. I'm legal, so I can go on a trip legally without a chaperone, so that'll be fun, just a girl trip.''

Of her birthday plans, she added: ''I'm going to be 18! So [it will be] crazy!''