diff --git a/src-tauri/src/app/gui.rs b/src-tauri/src/app/gui.rs
index 9c48484..c547ec6 100644
--- a/src-tauri/src/app/gui.rs
+++ b/src-tauri/src/app/gui.rs
@@ -2,6 +2,7 @@ use std::{sync::{Arc, Mutex}, thread};
 
 use tracing::{error, info, debug};
 use tauri::{Manager, Window};
+use uuid::Uuid;
 
 use crate::{LAUNCHER_DIRECTORY, minecraft::{launcher::{LauncherData, LaunchingParameter}, prelauncher, progress::ProgressUpdate, auth::{MinecraftAccount, self}}, HTTP_CLIENT};
 use crate::app::api::{Branches, Changelog, ContentDelivery, News};
@@ -131,7 +132,16 @@ async fn run_client(build_id: u32, account_data: MinecraftAccount, options: Laun
 
     let (account_name, uuid, token, user_type) = match account_data {
         MinecraftAccount::MsaAccount { name, uuid, token, .. } => (name, uuid, token, "msa".to_string()),
-        MinecraftAccount::OfflineAccount { name, uuid } => (name, uuid, "-".to_string(), "legacy".to_string())
+        MinecraftAccount::OfflineAccount { name, uuid } => {
+            // A UUID of length less than 2 is invalid, so we generate a new one
+            let uuid = if uuid.len() < 2 {
+                Uuid::new_v4().to_string()
+            } else {
+                uuid
+            };
+
+            (name, uuid, "-".to_string(), "legacy".to_string())
+        }
     };
 
     let parameters = LaunchingParameter {