Apple is relieving concerns about the iPhone 5S’s Touch ID, saying it won’t store actual fingerprint images. But that’s only a concern if your sweaty, greasy fingers can get it to work at all.

Speaking with the Wall Street Journal, an Apple spokesperson confirmed that the iPhone 5S will only store fingerprint data that will remain encrypted. The user’s fingerprint will unlock the device and can also be used to verify purchases from Apple’s digital storefronts like iTunes and the App Store.

But Apple revealed that Touch ID may have some trouble reading fingerprints wet with sweat, lotion, grease, etc. That could make eating potato chips and unlocking your iPhone problematic.

In the report, Apple also suggests Touch ID could have difficulty reading fingerprints with scarring but that in those cases, most testers have been able to use a different finger.

In light of privacy concerns arising from the U.S. government’s widespread digital surveillance efforts, concerns bubbled up about Touch ID’s potential to create a huge name-to-fingerprint database.