AudioMixer class not recognized by Unity/MonoDevelop

Doesn’t come up in MonoDevelop’s autocompletion, gives me a compiler error if I try to use it anyway. From what I’ve seen of peoples’ code here, it should just work like

public AudioMixer blorp;
blorp = Resources.Load("Justworkdamnyou") as AudioMixer;

etc etc… Right? I thought it might’ve been a problem with me using MonoDevelop 2.8.2, on account of the awful folding bug in newer versions, but I did a clean second install of Unity, deleted the MonoDevelop folders in Appdata\Roaming, and it still happened.

What gives?

Did you add

using UnityEngine.Audio;