diff --git a/d2m/converters/user-to-mxid.js b/d2m/converters/user-to-mxid.js
index 35a3b5e..4d53a9c 100644
--- a/d2m/converters/user-to-mxid.js
+++ b/d2m/converters/user-to-mxid.js
@@ -5,6 +5,10 @@ const assert = require("assert")
 const passthrough = require("../../passthrough")
 const {select} = passthrough
 
+const SPECIAL_USER_MAPPINGS = new Map([
+	["1081004946872352958", ["clyde_ai", "clyde"]]
+])
+
 /**
  * Downcased and stripped username. Can only include a basic set of characters.
  * https://spec.matrix.org/v1.6/appendices/#user-identifiers
@@ -30,7 +34,7 @@ function downcaseUsername(user) {
 /** @param {string[]} preferences */
 function* generateLocalpartAlternatives(preferences) {
 	const best = preferences[0]
-	assert.ok(best)
+	assert(best)
 	// First, suggest the preferences...
 	for (const localpart of preferences) {
 		yield localpart
@@ -50,15 +54,18 @@ function* generateLocalpartAlternatives(preferences) {
  * @returns {string}
  */
 function userToSimName(user) {
-	assert.notEqual(user.discriminator, "0000", "cannot create user for a webhook")
+	if (!SPECIAL_USER_MAPPINGS.has(user.id)) { // skip this check for known special users
+		assert.notEqual(user.discriminator, "0000", `cannot create user for a webhook: ${JSON.stringify(user)}`)
+	}
 
 	// 1. Is sim user already registered?
 	const existing = select("sim", "sim_name", {user_id: user.id}).pluck().get()
 	if (existing) return existing
 
 	// 2. Register based on username (could be new or old format)
+	// (Unless it's a special user, in which case copy their provided mappings.)
 	const downcased = downcaseUsername(user)
-	const preferences = [downcased]
+	const preferences = SPECIAL_USER_MAPPINGS.get(user.id) || [downcased]
 	if (user.discriminator.length === 4) { // Old style tag? If user.username is unavailable, try the full tag next
 		preferences.push(downcased + user.discriminator)
 	}
diff --git a/d2m/converters/user-to-mxid.test.js b/d2m/converters/user-to-mxid.test.js
index e709473..b080115 100644
--- a/d2m/converters/user-to-mxid.test.js
+++ b/d2m/converters/user-to-mxid.test.js
@@ -1,6 +1,7 @@
 const {test} = require("supertape")
 const tryToCatch = require("try-to-catch")
 const assert = require("assert")
+const data = require("../../test/data")
 const {userToSimName} = require("./user-to-mxid")
 
 test("user2name: cannot create user for a webhook", async t => {
@@ -39,3 +40,7 @@ test("user2name: uses ID if name becomes too short", t => {
 test("user2name: uses ID when name has only disallowed characters", t => {
    t.equal(userToSimName({username: "!@#$%^&*", discriminator: "0001", id: "9"}), "9")
 })
+
+test("user2name: works on special user", t => {
+	t.equal(userToSimName(data.user.clyde_ai), "clyde_ai")
+})
diff --git a/test/data.js b/test/data.js
index 648c2c8..3e78802 100644
--- a/test/data.js
+++ b/test/data.js
@@ -183,6 +183,23 @@ module.exports = {
 			safety_alerts_channel_id: null
 		}
 	},
+	user: {
+		clyde_ai: {
+			id: "1081004946872352958",
+			username: "clyde",
+			avatar: "a_6170487d32fdfe9f988720ad80e6ab8c",
+			discriminator: "0000",
+			public_flags: 0,
+			premium_type: 2,
+			flags: 0,
+			bot: true,
+			banner: null,
+			accent_color: null,
+			global_name: "Clyde",
+			avatar_decoration_data: null,
+			banner_color: null
+		}
+	},
 	member: {
 		kumaccino: {
 			avatar: null,