diff --git a/includes/functions.php b/includes/functions.php
index 859f67ed..3099defc 100755
--- a/includes/functions.php
+++ b/includes/functions.php
@@ -338,9 +338,9 @@ function CSRFValidate()
 {
     if(isset($_POST['csrf_token'])) {
         $post_token   = $_POST['csrf_token'];
-        $header_token = $_SERVER['HTTP_X_CSRF_TOKEN'];
+        $header_token = $_SERVER['HTTP_X_CSRF_TOKEN'] ?? null;
 
-        if (empty($post_token) && empty($header_token)) {
+        if (empty($post_token) && is_null($header_token)) {
             return false;
         }
         $request_token = $post_token;
diff --git a/templates/dhcp/advanced.php b/templates/dhcp/advanced.php
index 041a9555..59db1be9 100644
--- a/templates/dhcp/advanced.php
+++ b/templates/dhcp/advanced.php
@@ -7,7 +7,7 @@
       <div class="input-group">
         <input type="hidden" name="no-resolv" value="0">
         <div class="form-check form-switch">
-          <input class="form-check-input" id="no-resolv" type="checkbox" name="no-resolv" value="1" <?php echo $conf['no-resolv'] ? ' checked="checked"' : "" ?> aria-describedby="no-resolv-description">
+          <input class="form-check-input" id="no-resolv" type="checkbox" name="no-resolv" value="1" <?php echo ($conf['no-resolv'] ?? false) ? ' checked="checked"' : '' ?> aria-describedby="no-resolv-description">
           <label class="form-check-label" for="no-resolv"><?php echo _("Only ever query DNS servers configured below") ?></label>
         </div>
         <p id="no-resolv-description">