diff --git a/lib/I18n.php b/lib/I18n.php
index c44b67e..174ed77 100644
--- a/lib/I18n.php
+++ b/lib/I18n.php
@@ -130,13 +130,26 @@ class I18n
         if ($argsCount > 1) {
             for ($i = 0; $i < $argsCount; ++$i) {
                 if (($i > 0 && !is_int($args[$i])) || strpos($args[0], '<a') === false) {
-                    $args[$i] = htmlentities($args[$i], ENT_QUOTES | ENT_XHTML | ENT_DISALLOWED, 'UTF-8');
+                    $args[$i] = self::encode($args[$i]);
                 }
             }
         }
         return call_user_func_array('sprintf', $args);
     }
 
+    /**
+     * encode HTML entities for output into an HTML5 document
+     *
+     * @access public
+     * @static
+     * @param  string $string
+     * @return string
+     */
+    public static function encode($string)
+    {
+        return htmlspecialchars($string, ENT_QUOTES | ENT_HTML5 | ENT_DISALLOWED, 'UTF-8', false);
+    }
+
     /**
      * loads translations
      *
diff --git a/tpl/bootstrap.php b/tpl/bootstrap.php
index d1e24ac..e2d9bc0 100644
--- a/tpl/bootstrap.php
+++ b/tpl/bootstrap.php
@@ -4,7 +4,7 @@ $isCpct = substr($template, 9, 8) === '-compact';
 $isDark = substr($template, 9, 5) === '-dark';
 $isPage = substr($template, -5) === '-page';
 ?><!DOCTYPE html>
-<html>
+<html lang="<?php echo I18n::_('en'); ?>">
 	<head>
 		<meta charset="utf-8" />
 		<meta http-equiv="X-UA-Compatible" content="IE=edge">
@@ -440,7 +440,7 @@ if (strlen($NOTICE)):
 ?>
 				<div role="alert" class="alert alert-info">
 					<span class="glyphicon glyphicon-info-sign" aria-hidden="true"></span>
-					<?php echo htmlspecialchars($NOTICE), PHP_EOL; ?>
+					<?php echo I18n::encode($NOTICE), PHP_EOL; ?>
 				</div>
 <?php
 endif;
@@ -460,11 +460,11 @@ endif;
 ?>
 				<div id="status" role="alert" class="alert alert-info<?php echo empty($STATUS) ? ' hidden' : '' ?>">
 					<span class="glyphicon glyphicon-info-sign" aria-hidden="true"></span>
-					<?php echo htmlspecialchars($STATUS), PHP_EOL; ?>
+					<?php echo I18n::encode($STATUS), PHP_EOL; ?>
 				</div>
 				<div id="errormessage" role="alert" class="<?php echo empty($ERROR) ? 'hidden' : '' ?> alert alert-danger">
 					<span class="glyphicon glyphicon-alert" aria-hidden="true"></span>
-					<?php echo htmlspecialchars($ERROR), PHP_EOL; ?>
+					<?php echo I18n::encode($ERROR), PHP_EOL; ?>
 				</div>
 				<noscript>
 					<div id="noscript" role="alert" class="alert alert-<?php echo $isDark ? 'error' : 'warning'; ?>">
@@ -504,7 +504,7 @@ endif;
 if (strlen($URLSHORTENER)):
 ?>
 					<p>
-						<button id="shortenbutton" data-shortener="<?php echo htmlspecialchars($URLSHORTENER); ?>" type="button" class="btn btn-<?php echo $isDark ? 'warning' : 'primary'; ?> btn-block">
+						<button id="shortenbutton" data-shortener="<?php echo I18n::encode($URLSHORTENER); ?>" type="button" class="btn btn-<?php echo $isDark ? 'warning' : 'primary'; ?> btn-block">
 						<span class="glyphicon glyphicon-send" aria-hidden="true"></span> <?php echo I18n::_('Shorten URL'), PHP_EOL; ?>
 					</button>
 					</p>
diff --git a/tpl/page.php b/tpl/page.php
index cc11d8e..99f73cd 100644
--- a/tpl/page.php
+++ b/tpl/page.php
@@ -1,7 +1,7 @@
 <?php
 use PrivateBin\I18n;
 ?><!DOCTYPE html>
-<html lang="en">
+<html lang="<?php echo I18n::_('en'); ?>">
 	<head>
 		<meta charset="utf-8" />
 		<meta name="robots" content="noindex" />
@@ -67,7 +67,7 @@ endif;
 <?php
 if (strlen($NOTICE)):
 ?>
-				<span class="blink">▶</span> <?php echo htmlspecialchars($NOTICE);
+				<span class="blink">▶</span> <?php echo I18n::encode($NOTICE);
 endif;
 ?>
 			</div>
@@ -97,8 +97,8 @@ endif;
 		<section>
 			<article>
 				<div id="loadingindicator" class="hidden"><?php echo I18n::_('Loading…'); ?></div>
-				<div id="status"><?php echo htmlspecialchars($STATUS); ?></div>
-				<div id="errormessage" class="hidden"><?php echo htmlspecialchars($ERROR); ?></div>
+				<div id="status"><?php echo I18n::encode($STATUS); ?></div>
+				<div id="errormessage" class="hidden"><?php echo I18n::encode($ERROR); ?></div>
 				<div id="toolbar">
 					<button id="newbutton" class="reloadlink hidden"><img src="img/icon_new.png" width="11" height="15" alt="" /><?php echo I18n::_('New'); ?></button>
 					<button id="retrybutton" class="reloadlink hidden"><?php echo I18n::_('Retry'), PHP_EOL; ?></button>
@@ -207,7 +207,7 @@ endif;
 <?php
 if (strlen($URLSHORTENER)):
 ?>
-					<button id="shortenbutton" data-shortener="<?php echo htmlspecialchars($URLSHORTENER); ?>"><img src="img/icon_shorten.png" width="13" height="15" /><?php echo I18n::_('Shorten URL'); ?></button>
+					<button id="shortenbutton" data-shortener="<?php echo I18n::encode($URLSHORTENER); ?>"><img src="img/icon_shorten.png" width="13" height="15" /><?php echo I18n::_('Shorten URL'); ?></button>
 <?php
 endif;
 ?>
diff --git a/tst/I18nTest.php b/tst/I18nTest.php
index 658ceb1..ffdc567 100644
--- a/tst/I18nTest.php
+++ b/tst/I18nTest.php
@@ -159,7 +159,11 @@ class I18nTest extends PHPUnit_Framework_TestCase
     {
         $_SERVER['HTTP_ACCEPT_LANGUAGE'] = 'foobar';
         I18n::loadTranslations();
-        $this->assertEquals('some ' . htmlentities('&<>"\'/`=', ENT_QUOTES | ENT_XHTML | ENT_DISALLOWED, 'UTF-8') . ' + 1', I18n::_('some %s + %d', '&<>"\'/`=', 1), 'browser language en');
+        $input = '&<>"\'/`=';
+        $result = htmlspecialchars($input, ENT_QUOTES | ENT_HTML5 | ENT_DISALLOWED, 'UTF-8', false);
+        $this->assertEquals($result, I18n::encode($input), 'encodes HTML entities');
+        $this->assertEquals('<a>some ' . $result . ' + 1</a>', I18n::_('<a>some %s + %d</a>', $input, 1), 'encodes parameters in translations');
+        $this->assertEquals($result . $result, I18n::_($input . '%s', $input), 'encodes message ID as well, when no link');
     }
 
     public function testMessageIdsExistInAllLanguages()
