diff --git a/bureau/class/m_err.php b/bureau/class/m_err.php
index 74a8637f..75465ab7 100644
--- a/bureau/class/m_err.php
+++ b/bureau/class/m_err.php
@@ -96,9 +96,11 @@ class m_err {
       $str = _("err_".$this->clsid."_".$this->error)."\n";
     }
     $args = $this->param;
-    array_unshift($args, $str);
-    $msg = call_user_func_array("sprintf", $args);
-    return $msg;
+    if (is_array($args)) {
+      array_unshift($args, $str);
+      $msg = call_user_func_array("sprintf", $args);
+      return $msg;
+    } else return "";
   }
 
   /**