diff --git a/src/api/client/account/mod.rs b/src/api/client/account/mod.rs
index b54ef029d..ac6a24096 100644
--- a/src/api/client/account/mod.rs
+++ b/src/api/client/account/mod.rs
@@ -49,39 +49,16 @@ pub(crate) async fn get_register_available_route(
 	ClientIp(client): ClientIp,
 	body: Ruma<get_username_availability::v3::Request>,
 ) -> Result<get_username_availability::v3::Response> {
-	// Validate user id
-	let user_id =
-		match UserId::parse_with_server_name(&body.username, services.globals.server_name()) {
-			| Ok(user_id) => {
-				if let Err(e) = user_id.validate_strict() {
-					return Err!(Request(InvalidUsername(debug_warn!(
-						"Username {} contains disallowed characters or spaces: {e}",
-						body.username
-					))));
-				}
-
-				user_id
-			},
-			| Err(e) => {
-				return Err!(Request(InvalidUsername(debug_warn!(
-					"Username {} is not valid: {e}",
-					body.username
-				))));
-			},
-		};
-
-	// Check if username is creative enough
-	if services.users.exists(&user_id).await {
-		return Err!(Request(UserInUse("User ID is not available.")));
-	}
-
-	if let Some(ClientIdentity::Appservice { appservice_info, .. }) = &body.identity
-		&& !appservice_info.is_user_match(&user_id)
-	{
-		return Err!(Request(Exclusive("Username is not in an appservice namespace.")));
-	} else if services.appservice.is_exclusive_user_id(&user_id).await {
-		return Err!(Request(Exclusive("Username is reserved by an appservice.")));
-	}
+	let _ = services
+		.users
+		.determine_registration_user_id(
+			Some(body.username.clone()),
+			None,
+			body.identity
+				.as_ref()
+				.and_then(ClientIdentity::appservice_info),
+		)
+		.await?;
 
 	Ok(get_username_availability::v3::Response::new(true))
 }
@@ -109,8 +86,7 @@ pub(crate) async fn change_password_route(
 	ClientIp(client): ClientIp,
 	body: Ruma<change_password::v3::Request>,
 ) -> Result<change_password::v3::Response> {
-	let identity = if let Some(identity) = body.identity.as_ref()
-	{
+	let identity = if let Some(identity) = body.identity.as_ref() {
 		// A signed-in user is trying to change their password, prompt them for their
 		// existing one
 
diff --git a/src/api/client/account/threepid.rs b/src/api/client/account/threepid.rs
index 9594a0628..abe669523 100644
--- a/src/api/client/account/threepid.rs
+++ b/src/api/client/account/threepid.rs
@@ -122,7 +122,12 @@ pub(crate) async fn add_3pid_route(
 	// Require password auth to add an email
 	let _ = services
 		.uiaa
-		.authenticate_password(&body.auth, body.identity.sender_user(), body.identity.sender_device(), None)
+		.authenticate_password(
+			&body.auth,
+			body.identity.sender_user(),
+			body.identity.sender_device(),
+			None,
+		)
 		.await?;
 
 	let email = services
diff --git a/src/api/client/well_known.rs b/src/api/client/well_known.rs
index e7d35ca90..749571f99 100644
--- a/src/api/client/well_known.rs
+++ b/src/api/client/well_known.rs
@@ -3,8 +3,7 @@ use conduwuit::{Err, Result};
 use ruma::{
 	api::client::discovery::{
 		discover_homeserver::{self, HomeserverInfo},
-		discover_policy_server,
-		discover_support,
+		discover_policy_server, discover_support,
 	},
 	assign,
 };
diff --git a/src/api/router/auth.rs b/src/api/router/auth.rs
index 7d4f73c64..a2f4a4ad3 100644
--- a/src/api/router/auth.rs
+++ b/src/api/router/auth.rs
@@ -157,7 +157,9 @@ impl CheckAuth for AccessToken {
 		query: AuthQueryParams,
 		route: TypeId,
 	) -> Result<Self::Identity> {
-		if let Some((sender_user, sender_device, status)) = services.users.find_from_token(&output).await {
+		if let Some((sender_user, sender_device, status)) =
+			services.users.find_from_token(&output).await
+		{
 			// If the token is expired we return a soft logout
 			if matches!(status, AccessTokenStatus::Expired) {
 				return Err(Error::Request(
diff --git a/src/service/uiaa/mod.rs b/src/service/uiaa/mod.rs
index 184d7d90f..be3eb5d52 100644
--- a/src/service/uiaa/mod.rs
+++ b/src/service/uiaa/mod.rs
@@ -5,7 +5,6 @@ use std::{
 };
 
 use conduwuit::{Err, Error, Result, error, utils};
-use futures::future::OptionFuture;
 use lettre::Address;
 use ruma::{
 	DeviceId, UserId,
@@ -254,8 +253,7 @@ impl Service {
 
 		let session_metadata = if let Some(initiator) = initiator {
 			let is_oauth = if let Some(device_id) = initiator.device_id {
-				self
-					.services
+				self.services
 					.oauth
 					.get_session_info_for_device(initiator.user_id, device_id)
 					.await