diff --git a/class/dureefield.php b/class/dureefield.php
index 9b3aab6dcdcb2987fb8a18a644e1ea371925d5ca..6e75866d01b5ab1ece0d633a270f471e94cd1811 100644
--- a/class/dureefield.php
+++ b/class/dureefield.php
@@ -14,7 +14,7 @@ class DureeField extends Field
     public function validate()
     {
         $this->value = $_POST[$this->name];
-        if (this->value > -1) {
+        if ($this->value > -1) {
             return true;
         }
         return false;