diff --git a/User.php b/User.php
index c07dd5e..5e8487e 100644
--- a/User.php
+++ b/User.php
@@ -19,11 +19,11 @@
     public bool $privacy_policy_signed;
     public bool $author;
     public $accepted_paper_id;
-    public $participation_confirmed;
+    public bool $participation_confirmed;
     public $participation_confirmed_at;
     public bool $student;
     public bool $conference_dinner;
-    public $total_costs;
+    public float $total_due;
 
     function __construct()
     {
@@ -47,7 +47,7 @@
         $this->participation_confirmed_at = "";
         $this->student = false;
         $this->conference_dinner = false;
-        $this->total_costs = 0;
+        $this->total_due = 0.0;
     }
 
     function __construct1(object $data)
@@ -117,6 +117,8 @@
                 if (is_bool($value)) {
                     if ($value) $value = "yes";
                     else $value = "no";
+                } elseif(is_float($value)) {
+                    $key .= " €";
                 }
                 $value = str_replace("\r\n", "<br>", $value);
                 $key = str_replace("_", " ", ucfirst($key));