diff --git a/install/froxlor.sql b/install/froxlor.sql
index 2a8df7f1..afac1f80 100644
--- a/install/froxlor.sql
+++ b/install/froxlor.sql
@@ -797,9 +797,10 @@ CREATE TABLE `panel_diskspace_admins` (
 
 DROP TABLE IF EXISTS `panel_languages`;
 CREATE TABLE `panel_languages` (
-  `id` int(11) unsigned NOT NULL auto_increment,
-  `language` varchar(30) NOT NULL default '',
-  `file` varchar(255) NOT NULL default '',
+  `id` int(11) unsigned NOT NULL AUTO_INCREMENT,
+  `language` varchar(30) NOT NULL DEFAULT '',
+  `iso` char(3) NOT NULL DEFAULT 'foo',
+  `file` varchar(255) NOT NULL DEFAULT '',
   PRIMARY KEY  (`id`)
 ) ENGINE=MyISAM ;
 
@@ -807,23 +808,24 @@ CREATE TABLE `panel_languages` (
 # Dumping data for table `panel_languages`
 #
 
-INSERT INTO `panel_languages` VALUES (1, 'Deutsch', 'lng/german.lng.php');
-INSERT INTO `panel_languages` VALUES (2, 'English', 'lng/english.lng.php');
-INSERT INTO `panel_languages` VALUES (3, 'Français', 'lng/french.lng.php');
-INSERT INTO `panel_languages` VALUES (4, 'Chinese', 'lng/zh-cn.lng.php');
-INSERT INTO `panel_languages` VALUES (5, 'Catalan', 'lng/catalan.lng.php');
-INSERT INTO `panel_languages` VALUES (6, 'Español', 'lng/spanish.lng.php');
-INSERT INTO `panel_languages` VALUES (7, 'Português', 'lng/portugues.lng.php');
-INSERT INTO `panel_languages` VALUES (8, 'Russian', 'lng/russian.lng.php');
-INSERT INTO `panel_languages` VALUES (9, 'Danish', 'lng/danish.lng.php');
-INSERT INTO `panel_languages` VALUES (10, 'Italian', 'lng/italian.lng.php');
-INSERT INTO `panel_languages` VALUES (11, 'Bulgarian', 'lng/bulgarian.lng.php');
-INSERT INTO `panel_languages` VALUES (12, 'Slovak', 'lng/slovak.lng.php');
-INSERT INTO `panel_languages` VALUES (13, 'Dutch', 'lng/dutch.lng.php');
-INSERT INTO `panel_languages` VALUES (14, 'Hungarian', 'lng/hungarian.lng.php');
-INSERT INTO `panel_languages` VALUES (15, 'Swedish', 'lng/swedish.lng.php');
-INSERT INTO `panel_languages` VALUES (16, 'Czech', 'lng/czech.lng.php');
-INSERT INTO `panel_languages` VALUES (17, 'Polski', 'lng/polish.lng.php');
+INSERT INTO `panel_languages` (`id`, `language`, `iso`, `file`) VALUES
+    (1, 'Deutsch', 'de', 'lng/german.lng.php'),
+    (2, 'English', 'en', 'lng/english.lng.php'),
+    (3, 'Français', 'fr', 'lng/french.lng.php'),
+    (4, 'Chinese', 'zh', 'lng/zh-cn.lng.php'),
+    (5, 'Catalan', 'ca', 'lng/catalan.lng.php'),
+    (6, 'Español', 'es', 'lng/spanish.lng.php'),
+    (7, 'Português', 'pt', 'lng/portugues.lng.php'),
+    (8, 'Russian', 'ru', 'lng/russian.lng.php'),
+    (9, 'Danish', 'da', 'lng/danish.lng.php'),
+    (10, 'Italian', 'it', 'lng/italian.lng.php'),
+    (11, 'Bulgarian', 'bg', 'lng/bulgarian.lng.php'),
+    (12, 'Slovak', 'sk', 'lng/slovak.lng.php'),
+    (13, 'Dutch', 'nl', 'lng/dutch.lng.php'),
+    (14, 'Hungarian', 'hu', 'lng/hungarian.lng.php'),
+    (15, 'Swedish', 'sv', 'lng/swedish.lng.php'),
+    (16, 'Czech', 'cz', 'lng/czech.lng.php'),
+    (17, 'Polski', 'pl', 'lng/polish.lng.php');
 
 # --------------------------------------------------------
 
diff --git a/install/updates/froxlor/0.9/update_0.9.inc.php b/install/updates/froxlor/0.9/update_0.9.inc.php
index 0cf4a5c2..ed03caba 100644
--- a/install/updates/froxlor/0.9/update_0.9.inc.php
+++ b/install/updates/froxlor/0.9/update_0.9.inc.php
@@ -1832,6 +1832,70 @@ if(isFroxlorVersion('0.9.27')) {
 	if ($db->num_rows($handle) < 1) {
 		$db->query("INSERT INTO `panel_settings` (`settinggroup`, `varname`, `value`) VALUES ('phpfpm', 'aliasconfigdir', '/var/www/php-fpm/');");
 	}
+	
+	// Insert ISO-Codes into database. Default value is foo, which is not a valid language code.
+	$db->query("ALTER TABLE  `panel_languages` ADD  `iso` CHAR( 3 ) NOT NULL DEFAULT  'foo' AFTER  `language`");
 
+    $handle = $db->query("SELECT `language` FROM `panel_languages` WHERE `iso`='foo'");
+    
+    $langauges = $db->fetch_array($handle);
+    foreach($languages as $language){    
+        switch ($language) {
+            case "Deutsch":
+                $db->query("UPDATE `panel_languages` SET `iso`='de' WHERE `language` = 'Deutsch'");
+                break;
+            case "English":
+                $db->query("UPDATE `panel_languages` SET `iso`='en' WHERE `language` = 'English'");
+                break;
+            case "Fran&ccedil;ais":
+                $db->query("UPDATE `panel_languages` SET `iso`='fr' WHERE `language` = 'Fran&ccedil;ais'");
+                break;
+            case "Chinese":
+                $db->query("UPDATE `panel_languages` SET `iso`='zh' WHERE `language` = 'Chinese'");
+                break;
+            case "Catalan":
+                $db->query("UPDATE `panel_languages` SET `iso`='ca' WHERE `language` = 'Catalan'");
+                break;
+            case "Espa&ntilde;ol":
+                $db->query("UPDATE `panel_languages` SET `iso`='es' WHERE `language` = 'Espa&ntilde;ol'");
+                break;
+            case "Portugu&ecirc;s":
+                $db->query("UPDATE `panel_languages` SET `iso`='pt' WHERE `language` = 'Portugu&ecirc;s'");
+                break;
+            case "Danish":
+                $db->query("UPDATE `panel_languages` SET `iso`='da' WHERE `language` = 'Danish'");
+                break;
+            case "Italian":
+                $db->query("UPDATE `panel_languages` SET `iso`='it' WHERE `language` = 'Italian'");
+                break;
+            case "Bulgarian":
+                $db->query("UPDATE `panel_languages` SET `iso`='bg' WHERE `language` = 'Bulgarian'");
+                break;
+            case "Slovak":
+                $db->query("UPDATE `panel_languages` SET `iso`='sk' WHERE `language` = 'Slovak'");
+                break;
+            case "Dutch":
+                $db->query("UPDATE `panel_languages` SET `iso`='nl' WHERE `language` = 'Dutch'");
+                break;
+            case "Russian":
+                $db->query("UPDATE `panel_languages` SET `iso`='ru' WHERE `language` = 'Russian'");
+                break;
+            case "Hungarian":
+                $db->query("UPDATE `panel_languages` SET `iso`='hu' WHERE `language` = 'Hungarian'");
+                break;
+            case "Swedish":
+                $db->query("UPDATE `panel_languages` SET `iso`='sv' WHERE `language` = 'Swedish'");
+                break;
+            case "Czech":
+                $db->query("UPDATE `panel_languages` SET `iso`='cz' WHERE `language` = 'Czech'");
+                break;
+            case "Polski":
+                $db->query("UPDATE `panel_languages` SET `iso`='pl' WHERE `language` = 'Polski'");
+                break;
+            default:
+                showUpdateStep("Sorry, but I don't know the ISO-639 language code for ".$language.". Please update the entry in `panel_languages` manually.\n");
+        }
+    }
+    
  	updateToVersion('0.9.28-svn1');
 }
diff --git a/lib/init.php b/lib/init.php
index 1ad1f2f2..f71cbd53 100644
--- a/lib/init.php
+++ b/lib/init.php
@@ -266,6 +266,7 @@ else
 
 $langs = array();
 $languages = array();
+$iso = array();
 
 // query the whole table
 $query = 'SELECT * FROM `' . TABLE_PANEL_LANGUAGE . '` ';
@@ -275,6 +276,7 @@ $result = $db->query($query);
 while($row = $db->fetch_array($result))
 {
 	$langs[$row['language']][] = $row;
+	$iso[$row['iso']] = $row['language'];
 }
 
 // buildup $languages for the login screen
@@ -291,7 +293,7 @@ if (isset($userinfo['language']) && isset($languages[$userinfo['language']]))
 else
 {
 	if(!isset($userinfo['def_language'])
-	   || !isset($languages[$userinfo['def_language']]))
+	   || !isset($languages[$userinfo['def_language']]))// this will always evaluat  true, since it is the above statement inverted. @todo remove
 	{
 		if(isset($_GET['language'])
 		   && isset($languages[$_GET['language']]))
@@ -300,7 +302,22 @@ else
 		}
 		else
 		{
-			$language = $settings['panel']['standardlanguage'];
+			$accept_langs = explode(',',$_SERVER['HTTP_ACCEPT_LANGUAGE']);
+			for($i = 0; $i<count($accept_langs); $i++) {
+			    # this only works for most common languages. some (uncommon) languages have a 3 letter iso-code.
+			    # to be able to use these also, we would have to depend on the intl extension for php (using Locale::lookup or similar)
+			    # as long as froxlor does not support any of these languages, we can leave it like that.
+				if(isset($iso[substr($accept_langs[$i],0,2)])) {
+					$language=$iso[substr($accept_langs[$i],0,2)];
+					break;
+				}
+			}
+			unset($iso);
+			
+			// if HTTP_ACCEPT_LANGUAGES has no valid langs, use default (very unlikely)
+			if(!strlen($language)>0) {
+				$language = $settings['panel']['standardlanguage'];
+			}
 		}
 	}
 	else
@@ -309,6 +326,7 @@ else
 	}
 }
 
+
 // include every english language file we can get
 foreach($langs['English'] as $key => $value)
 {