diff --git a/src/controller-registry.js b/src/controller-registry.js
index 160f087..d75e91a 100644
--- a/src/controller-registry.js
+++ b/src/controller-registry.js
@@ -1,5 +1,7 @@
 /** @typedef {Promise & {signal: AbortSignal}} PromiseWithSignal */
-/** @typedef {(element: HTMLElement, detach: PromiseWithSignal) => void} Callback */
+/** @typedef {(element: HTMLElement, detached: PromiseWithSignal) => void} Callback */
+/** @typedef {new (element: HTMLElement, detached: PromiseWithSignal) => Object} ControllerClass */
+/** @typedef {Callback|ControllerClass} Controller */
 
 export class ControllerList {
 	/** @type {HTMLElement} */
@@ -105,6 +107,11 @@ export class ControllerRegistry {
 	/** @type {Map<string,Callback>} */
 	#defined = new Map()
 
+	/** @type {Map<string,Controller>} */
+	#lookup = new Map()
+	/** @type {Map<Controller,string>} */
+	#nameLookup = new Map()
+
 	#attribute
 
 	/** @typedef {Document|DocumentFragment|HTMLElement} Root */
@@ -141,20 +148,25 @@ export class ControllerRegistry {
 
 	/**
 	 * @param {string} name
-	 * @param {Callback} callback
+	 * @param {Controller} callback
 	 */
 	define(name, callback) {
+		if (this.#nameLookup.has(callback)) console.warn(`Redefining controller ${this.#nameLookup.get(callback)} under new name ${name}:`, callback)
+
+		this.#lookup.set(name, callback)
+		this.#nameLookup.set(callback, name)
+
 		if (("function" == typeof callback) && callback.prototype) {
 			callback = async (element, disconnected) => {
 				const {proxy, revoke} = Proxy.revocable(element, {})
-				const controller = new callback(proxy, disconnected)
+				const controller = new /** @type {ControllerClass} */(callback)(proxy, disconnected)
 				await disconnected
 				revoke()
 				if ("detach" in controller) controller.detach(element)
 			}
 		}
 
-		this.#defined.set(name, callback)
+		this.#defined.set(name, /** @type {Callback} */(callback))
 
 		const waitingList = this.#waiting.get(name)
 
@@ -162,13 +174,42 @@ export class ControllerRegistry {
 			this.#attach(element, name)
 		}
 		this.#waiting.delete(name)
+
+		if (this.#whenDefined.has(name)) {
+			this.#whenDefined.get(name)[1]?.()
+		}
 	}
 
 	/** Gets a controller associated with a given name
 	 * @param {string} name
 	 */
 	get(name) {
-		return this.#defined.get(name)
+		return this.#lookup.get(name)
+	}
+
+	/** Gets the name a controller is registered with
+	 * @param {Controller} controller
+	 */
+	getName(controller) {
+		return this.#nameLookup.get(controller)
+	}
+
+	/** @type {Map<string,[Promise, ()=>void]>} */
+	#whenDefined = new Map()
+	/**
+	 * @param {string} name
+	 */
+	whenDefined(name) {
+		if (!this.#whenDefined.has(name)) {
+			if (this.#defined.has(name)) {
+				this.#whenDefined.set(name, [Promise.resolve(), undefined])
+			} else {
+				let resolve
+				const promise = new Promise(_resolve => {resolve = _resolve})
+				this.#whenDefined.set(name, [promise, resolve])
+			}
+		}
+		return this.#whenDefined.get(name)[0]
 	}
 
 	/** @type {WeakMap<HTMLElement,ControllerList>} */
@@ -192,18 +233,10 @@ export class ControllerRegistry {
 		const attached = this.#attached.get(element)
 		if (attached)
 			return [...attached.entries().filter(pair => pair[1]).map(pair => pair[0])]
-		else
+			else
 			return []
 	}
 
-	getName(controller) {
-		// TODO: Return name of controller
-	}
-
-	whenDefined(name) {
-		// TODO: Return a promise
-	}
-
 	/** @param {HTMLElement} element */
 	#update(element) {
 		const names = this.#getControllerNames(element)
@@ -238,7 +271,7 @@ export class ControllerRegistry {
 		if (!this.#attached.has(element)) this.#attached.set(element, new Map())
 		const attached = this.#attached.get(element)
 
-		const callback = this.get(name)
+		const callback = this.#defined.get(name)
 
 		if (callback) {
 			if (attached.has("name") && attached.get("name")) return console.warn(`Controller ${name} already fully attached`, element)