College students have a new way to protect themselves against date-rape drugs.

The University of New Mexico is providing tech-savvy coasters to its students that can test for the presence of drugs such as GHB and ketamine with a single drop of one’s drink.

If the coaster turns blue, the drink has tested positive for the drug. Abusers often spike a victim’s drink when they are not paying attention, and the drugs are typically odorless and colorless.