diff --git a/htdocs/code.js b/htdocs/code.js
index 727c07a9d27747cde0f4947414d80d2b64914b53..437c76d37c3338fcfaa79d586345a617c02aace2 100644
--- a/htdocs/code.js
+++ b/htdocs/code.js
@@ -179,7 +179,7 @@ $(document).ready(function()
 		document.getElementById('btn').disabled = true;
 		var isInError = false;
 		var username = $("#username").val().trim();
-		if( !/^[A-Za-z0-9_\-\.]{3,30}$/.test(username)) {
+		if( !/^[a-z0-9_\-\.]{3,30}$/.test(username)) {
 			var message = getStr('error_invalid_username');
 			message = message.replace("@@@username@@@",username);
 			showError('unet',message,'usernamerror');
diff --git a/htdocs/langs/de.strings b/htdocs/langs/de.strings
index c355f1b8621deb8338a14950504156caeff6066b..29ac85f4bf477a549cf95674c9a55bfc1c060f7c 100644
--- a/htdocs/langs/de.strings
+++ b/htdocs/langs/de.strings
@@ -9,7 +9,7 @@ form_placeholder_username_short ===== max.mustermann
 form_label_password ===== Passwort eingeben
 form_label_repassword ===== Passwort wiederholen
 form_label_button ===== Los!
-error_invalid_username ===== Ung&uuml;ltiger Benutzername "@@@username@@@".<br />L&auml;nge: 3 bis 30, erlaubte Zeichen: a-z, A-Z ,0-9, _, -, .
+error_invalid_username ===== Ung&uuml;ltiger Benutzername "@@@username@@@".<br />L&auml;nge: 3 bis 30, erlaubte Zeichen: a-z, 0-9, _, -, .
 error_invalid_displayname ===== Ung&uuml;ltiger Anzeigename "@@@username@@@".<br />L&auml;nge: 3 bis 30
 error_incorrect_pw_length ===== Falsche Passwortl&auml;nge. L&auml;nge: 5 bis 32
 error_pw_mismatch ===== Die Passw&ouml;rter stimmen nicht &uuml;berein
diff --git a/htdocs/langs/en.strings b/htdocs/langs/en.strings
index f7e3e5b275324fc42143e76adb07839e88e942ed..50aaa622e97d69f32e15a6a876e0c8945c10a9e7 100644
--- a/htdocs/langs/en.strings
+++ b/htdocs/langs/en.strings
@@ -9,7 +9,7 @@ form_placeholder_username_short ===== john.doe
 form_label_password ===== Enter password
 form_label_repassword ===== Repeat password
 form_label_button ===== Go!
-error_invalid_username ===== Invalid username "@@@username@@@".<br />Length: 3 to 30, allowed chars: a-z,0-9, _, -, .
+error_invalid_username ===== Invalid username "@@@username@@@".<br />Length: 3 to 30, allowed chars: a-z, 0-9, _, -, .
 error_invalid_displayname ===== Invalid display name "@@@username@@@".<br />Length: 3 to 30
 error_incorrect_pw_length ===== Incorrect password length: Required length is 5 to 32
 error_pw_mismatch ===== Passwords do not match
diff --git a/htdocs/langs/es.strings b/htdocs/langs/es.strings
index 0bc627cbbb1a5cfacf4de5313541abde5f0b9bae..0c6443ffaab465c3b3ce2f412f6cfc896d93198b 100644
--- a/htdocs/langs/es.strings
+++ b/htdocs/langs/es.strings
@@ -9,7 +9,7 @@ form_placeholder_username_short ===== john.doe
 form_label_password ===== Ingresar contrase&#xF1;a
 form_label_repassword ===== Repite contrase&#xF1;a
 form_label_button ===== &#xA1;Vam&#xF3;s!
-error_invalid_username ===== Nombre de usuario inv&#xE1;lido "@@username@@@". Longitud: de 3 a 30, caracteres permitidos: a-z, A-Z, 0-9, _, -, .
+error_invalid_username ===== Nombre de usuario inv&#xE1;lido "@@username@@@". Longitud: de 3 a 30, caracteres permitidos: a-z, 0-9, _, -, .
 error_invalid_displayname ===== Visualizaci&#xF3;n de Nombre inv&#xE1;lida "@@@username@@@".<br /> Longitud: de 3 a 30
 error_incorrect_pw_length ===== Longitud de contrase&#xF1;a incorrecta: la longitud requerida es de 5 a 32
 error_pw_mismatch ===== Las contrase&#xF1;as no coinciden
diff --git a/htdocs/langs/fr.strings b/htdocs/langs/fr.strings
index d6bce26e1e0e002e9758cf9b1486033aadb0cb38..18f707d8d4634275f0247139c5afdbda71c6af0b 100644
--- a/htdocs/langs/fr.strings
+++ b/htdocs/langs/fr.strings
@@ -9,7 +9,7 @@ form_placeholder_username_short ===== jean.dupont
 form_label_password ===== Entrez votre mot de passe
 form_label_repassword ===== R&eacute;p&eacute;tez votre mot de passe
 form_label_button ===== Valider !
-error_invalid_username ===== Nom d&rsquo;utilisateur invalide "@@@username@@@".<br />Longueur : 3 &agrave; 30, caract&egrave;res autoris&eacute;s: a-z, A-Z ,0-9, _, -, .
+error_invalid_username ===== Nom d&rsquo;utilisateur invalide "@@@username@@@".<br />Longueur : 3 &agrave; 30, caract&egrave;res autoris&eacute;s: a-z, 0-9, _, -, .
 error_invalid_displayname ===== Nom d&rsquo;affichage invalide "@@@username@@@".<br />Longueur : 3 &agrave; 30
 error_incorrect_pw_length ===== Longueur de mot de passe incorrecte : Requiert une longueur de 5 &agrave; 32 caract&egrave;res
 error_pw_mismatch ===== Les mots de passes ne sont pas identiques
diff --git a/htdocs/langs/it.strings b/htdocs/langs/it.strings
index d53853cebfb8e2fe36dddd1dce106cb3da0fdd8e..9df206716dc530d12ca8cb18bf6647e163be8955 100644
--- a/htdocs/langs/it.strings
+++ b/htdocs/langs/it.strings
@@ -9,7 +9,7 @@ form_placeholder_username_short ===== mario.rossi
 form_label_password ===== Inserisci la password
 form_label_repassword ===== Ripeti la password
 form_label_button ===== Crea!
-error_invalid_username ===== Nome utente "@@@username@@@" non valido.<br />Lunghezza: da 3 a 30, caratteri consentiti: a-z, A-Z ,0-9, _, -, .
+error_invalid_username ===== Nome utente "@@@username@@@" non valido.<br />Lunghezza: da 3 a 30, caratteri consentiti: a-z, 0-9, _, -, .
 error_invalid_displayname ===== Nome visualizzato "@@@username@@@" non valido.<br />Lunghezza: da 3 a 30
 error_incorrect_pw_length ===== Password non valida: si richiede una lunghezza compresa tra 5 e 32
 error_pw_mismatch ===== Le password non combaciano