diff --git a/crates/backend/src/controller/user.rs b/crates/backend/src/controller/user.rs
index dd3eac2..38d8306 100644
--- a/crates/backend/src/controller/user.rs
+++ b/crates/backend/src/controller/user.rs
@@ -13,8 +13,8 @@ pub fn setup(cfg: &mut actix_web::web::ServiceConfig) {
 
 #[derive(Deserialize, Validate, ToSchema)]
 pub struct CreateUser {
-    #[validate(length(min = 4))]
-    /// Username (minimum 4 characters)
+    #[validate(length(min = 4, max = 255))]
+    /// Username (minimum 4 characters, maximum 255 characters)
     /// TODO: Don't allow spaces, only alphanumeric characters and underscores
     username: String,
     /// Full name of the user