to let me know, to inform me
Il fallait me prévenir avant d'ouvrir votre gueule.
You should have warned me before opening your mouth.
— Dans ses yeux (2009)
Please let me know.
T'allais partir en voyage sans me prévenir ?
Were you going on a trip without telling me?
Tu as bien fait de me prévenir.
You did well to warn me.
Veuillez me prévenir quand vous n'arriverez plus à entendre cela.
Please let me know when you can no longer hear this.
Well, you could have warned me.
Notify me?