Ali Lohan  shorts butt lindsay lohan underage

Ali Lohan is looking out for big sis Lindsay.

Lindsay's little sis was spotted outside the actress' Venice home Tuesday; she seems to be checking the perimeter.

17-year-old Ali sported a classic collared shirt and some retro high-waisted shorts for her stealth mission.

She's looking lovely, and growing her hair long like Lindsay!

Maybe she was there to show support for her sis, who is scheduled to start court-mandated community service soon.