diff --git a/references_dialog.info b/references_dialog.info
index 73dfcfe..bb3da11 100644
--- a/references_dialog.info
+++ b/references_dialog.info
@@ -5,3 +5,4 @@ backdrop = 1.x
 type = module
 dependencies[] = field
 dependencies[]= entity_plus
+dependencies[]= references
diff --git a/references_dialog.module b/references_dialog.module
index f774762..062964c 100644
--- a/references_dialog.module
+++ b/references_dialog.module
@@ -757,10 +757,10 @@ function references_dialog_field_widget_settings_form($field, $instance) {
       '#description'      => t('Select the method used to collect autocomplete suggestions. Note that <em>Contains</em> can cause performance issues on sites with thousands of nodes.'),
     );
     $form['size'] = array(
-      '#type'             => 'textfield',
+      '#type'             => 'number',
       '#title'            => t('Size of textfield'),
       '#default_value'    => $settings['size'],
-      '#element_validate' => array('_element_validate_integer_positive'),
+      '#min' => 0,
       '#required'         => TRUE,
     );
   }