diff --git a/GameEngine/Database/DatabaseUserQueries.php b/GameEngine/Database/DatabaseUserQueries.php
index e36734c1..41e6f8e2 100644
--- a/GameEngine/Database/DatabaseUserQueries.php
+++ b/GameEngine/Database/DatabaseUserQueries.php
@@ -58,7 +58,7 @@ trait DatabaseUserQueries {
         ? strtolower(trim((string) SERVER_LANG))
         : 'en';
 
-    $allowedLanguages = ['en', 'fr', 'it', 'ro', 'zh'];
+    $allowedLanguages = ['en', 'es', 'fr', 'it', 'ro', 'zh'];
 
     if (!in_array($serverLang, $allowedLanguages, true)) {
         $serverLang = 'en';
@@ -923,4 +923,4 @@ trait DatabaseUserQueries {
     }
     return empty($errors) ? true : $errors;
 	}
-}
\ No newline at end of file
+}
diff --git a/GameEngine/Lang/it.php b/GameEngine/Lang/it.php
index 19a1977f..613c4fd5 100755
--- a/GameEngine/Lang/it.php
+++ b/GameEngine/Lang/it.php
@@ -2257,6 +2257,4 @@ tz_def('MANUAL_INTRO', "Questo aiuto di gioco ti permette di consultare informaz
 tz_def('MANUAL_NEW_FEATURES_DESC', "Queste sono novità che non troverai nella versione reale del gioco Travian T3.6. Qui puoi conoscere tutte le novità in dettaglio.");
 tz_def('MANUAL_FAQ', 'FAQ Travian');
 tz_def('MANUAL_FAQ_DESC', "Questo aiuto di gioco fornisce solo brevi informazioni. Maggiori informazioni sono disponibili sul");
-
-?>
 tz_def('ADM_SPANISH', 'Spagnolo');
diff --git a/tests/LanguageLoaderTest.php b/tests/LanguageLoaderTest.php
index 60c957a0..502c24aa 100644
--- a/tests/LanguageLoaderTest.php
+++ b/tests/LanguageLoaderTest.php
@@ -30,10 +30,16 @@ function run_language_case($language)
             'tribe' => 'Romains',
             'welcome' => 'Bienvenue sur le Test Server!',
         ],
+        'es' => [
+            'tribe' => 'Romanos',
+            'welcome' => 'Welcome to Test Server',
+            'spanish_label' => 'Espanol',
+        ],
         'it' => [
             'tribe' => 'Romani',
             'welcome' => 'Benvenuto in Test Server',
             'fallback' => ['TRIBE7', 'Egyptians'],
+            'spanish_label' => 'Spagnolo',
         ],
         'ro' => [
             'tribe' => 'Romani',
@@ -60,8 +66,11 @@ function run_language_case($language)
     define('SPEED', 1);
 
     require dirname(__DIR__) . '/GameEngine/Lang/loader.php';
+    ob_start();
     $loaded = tz_load_language($language);
+    $unexpectedOutput = ob_get_clean();
 
+    assert_same('', $unexpectedOutput, $language . ': loading a locale must not emit output');
     assert_same($expected[$language]['tribe'], TRIBE1, $language . ': selected constants must win');
     assert_same(
         $expected[$language]['welcome'],
@@ -75,6 +84,14 @@ function run_language_case($language)
         assert_same($value, constant($constant), $language . ': missing constant must fall back to English');
     }
 
+    if (isset($expected[$language]['spanish_label'])) {
+        assert_same(
+            $expected[$language]['spanish_label'],
+            ADM_SPANISH,
+            $language . ': selected locale must define the Spanish language label'
+        );
+    }
+
     $fixtureDirectory = __DIR__ . '/fixtures/languages';
     $fixture = tz_load_language('xx', $fixtureDirectory);
     assert_same(
@@ -118,7 +135,7 @@ if (isset($argv[1])) {
     exit(0);
 }
 
-$languages = ['en', 'fr', 'it', 'ro', 'zh'];
+$languages = ['en', 'es', 'fr', 'it', 'ro', 'zh'];
 foreach ($languages as $language) {
     $pipes = [];
     $process = proc_open(
@@ -149,4 +166,4 @@ foreach ($languages as $language) {
     echo $stdout;
 }
 
-echo "PASS language loader: 5 locales\n";
+echo "PASS language loader: 6 locales\n";
diff --git a/tests/regression/RegistrationLanguageTest.php b/tests/regression/RegistrationLanguageTest.php
new file mode 100644
index 00000000..4d0c8ca7
--- /dev/null
+++ b/tests/regression/RegistrationLanguageTest.php
@@ -0,0 +1,96 @@
+<?php
+
+if (!isset($argv[1])) {
+    foreach (['es' => 'es', 'invalid' => 'en'] as $configured => $expected) {
+        $command = escapeshellarg(PHP_BINARY)
+            . ' '
+            . escapeshellarg(__FILE__)
+            . ' '
+            . escapeshellarg($configured)
+            . ' '
+            . escapeshellarg($expected);
+
+        passthru($command, $status);
+        if ($status !== 0) {
+            exit($status);
+        }
+    }
+
+    fwrite(STDOUT, "Registration language regression test passed.\n");
+    exit(0);
+}
+
+define('USER', 2);
+define('TB_PREFIX', 'test_');
+define('SERVER_LANG', $argv[1]);
+define('START_DATE', date('d.m.Y'));
+define('START_TIME', '00:00');
+define('PROTECTION', 0);
+
+require_once __DIR__ . '/../../GameEngine/Database/DatabaseUserQueries.php';
+
+final class RegistrationLanguageStatement
+{
+    public $insert_id = 42;
+
+    public function bind_param($types, &...$values)
+    {
+    }
+
+    public function execute()
+    {
+        return true;
+    }
+
+    public function close()
+    {
+    }
+}
+
+final class RegistrationLanguageConnection
+{
+    public function prepare($query)
+    {
+        return new RegistrationLanguageStatement();
+    }
+}
+
+final class RegistrationLanguageHarness
+{
+    use DatabaseUserQueries;
+
+    public $dblink;
+    public $language;
+
+    public function __construct()
+    {
+        $this->dblink = new RegistrationLanguageConnection();
+    }
+
+    public function updateUserField($ref, $field, $value, $switch)
+    {
+        if ($field === 'lang') {
+            $this->language = $value;
+        }
+    }
+
+    private function grantRegistrationGold($id)
+    {
+    }
+}
+
+$database = new RegistrationLanguageHarness();
+$id = $database->register('player', 'password', 'player@example.com', 1, '');
+
+if ($id !== 42) {
+    fwrite(STDERR, "Registration did not return the inserted account ID.\n");
+    exit(1);
+}
+
+if ($database->language !== $argv[2]) {
+    fwrite(
+        STDERR,
+        "Expected registration language {$argv[2]}; got {$database->language}.\n"
+    );
+    exit(1);
+}