Families should have enough cash set aside to last them three days in case of an emergency, the central bank of the Netherlands warned today.

It advised people to keep €70 per adult and €30 per child safe in hard currency in case electronic payments systems go down.

The bank cited the threat of cyberattacks — a growing risk given the increasingly fraught geopolitical situation — as one reason for consumers to stay prepared.

In April, a power blackout in Spain and Portugal caused severe but ultimately short-lived problems with payments systems.

The cash that’s set aside should be enough to cover “the minimum necessary expenses for a period of three days, such as for water, food, medicine, and transportation.”

The Dutch central bank also had some advice for merchants: They should have alternative payment systems in place, like scannable QR codes, in case point-of-sale terminals don’t work.

In March, the European Commission published a preparedness plan that recommended citizens stock three days’ worth of food to ensure supplies in case of emergencies like war or natural disasters.