1 files changed, 1 insertions, 0 deletions
diff --git a/lib/register.ts b/lib/register.ts
index 8b893d6c..a74ea640 100644
--- a/lib/register.ts
+++ b/lib/register.ts
@@ -21,6 +21,7 @@ export default async (user, ip) => {
   if (!valid.test(username))
     fail("Usernames can only have letters and numbers");
   if (reserved.includes(username)) fail("Invalid username");
+  if (username.includes("undefined")) fail("Invalid username");
 
   const id = v4();
   user.id = id;