diff --git a/library/Icinga/Web/Form.php b/library/Icinga/Web/Form.php
index dde9db41c..1a9cb5b97 100644
--- a/library/Icinga/Web/Form.php
+++ b/library/Icinga/Web/Form.php
@@ -491,7 +491,7 @@ class Form extends Zend_Form
      *
      * @param   array   $defaults   The values to populate the elements with
      */
-    public function setDefaults($defaults)
+    public function setDefaults(array $defaults)
     {
         $this->create($defaults);
         return parent::setDefaults($defaults);