diff --git a/src/routes/register/+server.ts b/src/routes/register/+server.ts
index 9a502af..f65cd02 100644
--- a/src/routes/register/+server.ts
+++ b/src/routes/register/+server.ts
@@ -60,7 +60,10 @@ export const POST = (async ({ request }) => {
 		}
 	}
 
-	if (uuid && (await User.findOne({ where: { uuid: uuid } }))) {
+	if (
+		(uuid && (await User.findOne({ where: { uuid: uuid } }))) ||
+		(!uuid && (await User.findOne({ where: { username: data.username } })))
+	) {
 		throw error(
 			400,
 			'Dein Minecraft-Account wurde bereits registriert.\n\nKontaktiere bitte einen Admin, falls diese ' +