pronoun verb agreement

[Eddie Gutia]

Below is a question from Verbal foundations strategy guide, page 36:

One who wishes to buy oneself a gift with funds from one's own company must first speak with one's accountant lest one run afoul of the law

Question: In the above sentence, run is the verb for the pronoun one. So I believe runs instead of run should be used. Can you please clarify?

[tim]

The "lest" is key here. This puts us into a hypothetical mode (please review the information on subjunctives if you haven't already) that causes the verb to be conjugated differently.

[RonPurewal]

... and, if you didn't know that one, there's certainly no reason to feel bad——this is far from "foundational" knowledge.