How to deal with v-for in vuejs when element has no id?

I often get this error related to the v-for directive.

Elements in iteration expect to have v-bind:key directive

When using a for loop like this.

<div v-for='person in people'> {{ person.name }} </div>

The problem is, in sometimes in rare cases, I have no id key for person. And I want to know what can be done in this case.