diff --git a/server/Cargo.toml b/server/Cargo.toml
index 0004284..209256a 100644
--- a/server/Cargo.toml
+++ b/server/Cargo.toml
@@ -22,6 +22,7 @@ ring = "0.17.8"
 const_format = "0.2.32"
 markdown = "0.3.0"
 usvg = "0.44.0"
+regex = "1.11.0"
 
 game = { path = "../game" }
 
diff --git a/server/src/manager/data.rs b/server/src/manager/data.rs
index 695dac4..8cf04a2 100644
--- a/server/src/manager/data.rs
+++ b/server/src/manager/data.rs
@@ -142,9 +142,11 @@ pub async fn thread_system(mut app:App, bus:Bus<protocol::QRPacket>)
                 app.log.log("Request: Register");
 
                 let mut is_valid = true;
+                let regex = regex::Regex::new(r"^[\p{L}\p{N}\p{Pd}\p{Pc}\p{Sm}\p{Sc}]{1,24}$").unwrap();
+
                 let invite = app.invite_tokens.get(&request.code).cloned();
                 if is_valid && invite.is_none() { response.status = STATUS_BAD_CODE; is_valid = false; }
-                if is_valid && request.handle.len() == 0 && request.handle.chars().count() <= 24 { response.status = STATUS_BAD_HANDLE; is_valid = false; }
+                if is_valid && !regex.is_match(&request.handle) { response.status = STATUS_BAD_HANDLE; is_valid = false; }
                 if is_valid && request.secret.len() == 0 { response.status = STATUS_BAD_SECRET; is_valid = false; }
 
                 if is_valid {
diff --git a/www/js/scene.js b/www/js/scene.js
index ca21386..1b290df 100644
--- a/www/js/scene.js
+++ b/www/js/scene.js
@@ -45,6 +45,14 @@ const SCENES = {
 
             let tb_handle = UI.textbox("handle", "user");
             tb_handle.setAttribute("maxlength", 24);
+            tb_handle.addEventListener("input", (event) => {
+                let value = event.target.value;
+                if(value.length == 0 || VALID.username(value)) {
+                    event.target.removeAttribute("class");
+                } else {
+                    event.target.setAttribute("class", "error");
+                }
+            })
 
             form.appendChild(UI.table(null, [
                 [ UI.label(LANG("handle"), "handle"), tb_handle ],
@@ -71,7 +79,7 @@ const SCENES = {
                 let invitation = code.value;
                 invitation = invitation.replace(/\-/g, '');
 
-                if(handle.value.length > 0 && handle.value.length < 24 && secret.value.length > 0 && invitation.length > 0) {
+                if(VALID.username(handle.value) && secret.value.length > 0 && invitation.length > 0) {
                     event.target.setAttribute("disabled", "");
 
                     let enc = new TextEncoder();
diff --git a/www/js/util.js b/www/js/util.js
index e20492d..5730272 100644
--- a/www/js/util.js
+++ b/www/js/util.js
@@ -283,3 +283,10 @@ const HEX = {
         return (hex.x >= 0 && hex.x < 3 && hex.y >= COLUMNS[hex.x].x && hex.y <= COLUMNS[hex.x].y);
     },
 };
+
+const VALID = {
+    username(text) {
+        const reg = /^[\p{L}\p{N}\p{Pd}\p{Pc}\p{Sm}\p{Sc}]{1,24}$/u;
+        return reg.test(text);
+    },
+};