diff --git a/src/invidious/routes/api/v1/authentication.cr b/src/invidious/routes/api/v1/authentication.cr
index b99a495a..d299bde9 100644
--- a/src/invidious/routes/api/v1/authentication.cr
+++ b/src/invidious/routes/api/v1/authentication.cr
@@ -39,7 +39,7 @@ module Invidious::Routes::API::V1::Authentication
         end
 
         if username.bytesize > 254
-          return error_json(401)
+          return error_json(401, "Username cannot be longer than 254 characters")
         end
 
         # See https://security.stackexchange.com/a/39851