diff --git a/data/web/inc/prerequisites.inc.php b/data/web/inc/prerequisites.inc.php
index b5f150fc..5a6ed18c 100644
--- a/data/web/inc/prerequisites.inc.php
+++ b/data/web/inc/prerequisites.inc.php
@@ -26,7 +26,7 @@ require_once 'inc/lib/Yubico.php';
 
 // U2F API
 require_once 'inc/lib/U2F.php';
-$u2f = new u2flib_server\U2F('https://' . $_SERVER['HTTP_HOST']);
+$u2f = new u2flib_server\U2F('https://' . $_SERVER['SERVER_NAME']);
 
 // PDO
 $dsn = "$database_type:host=$database_host;dbname=$database_name";
diff --git a/data/web/u2f_api.php b/data/web/u2f_api.php
index cd3a4ab6..ddeb1ece 100644
--- a/data/web/u2f_api.php
+++ b/data/web/u2f_api.php
@@ -3,7 +3,7 @@ require_once('inc/prerequisites.inc.php');
 $pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
 $pdo->setAttribute(PDO::ATTR_DEFAULT_FETCH_MODE, PDO::FETCH_OBJ);
 
-$u2f = new u2flib_server\U2F('https://' . $_SERVER['HTTP_HOST']);
+$u2f = new u2flib_server\U2F('https://' . $_SERVER['SERVER_NAME']);
 
 function getRegs($username) {
   global $pdo;
diff --git a/docs/first_steps.md b/docs/first_steps.md
index 91cfb581..2202794c 100644
--- a/docs/first_steps.md
+++ b/docs/first_steps.md
@@ -126,7 +126,6 @@ server {
     location / {
         proxy_pass http://127.0.0.1:8080/;
         proxy_redirect http://127.0.0.1:8080/ $scheme://$host:$server_port/;
-        proxy_set_header Host $host;
         proxy_set_header X-Real-IP $remote_addr;
         proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
         proxy_set_header X-Forwarded-Proto $scheme;