diff --git a/lightbox2.module b/lightbox2.module
index 14e1c7e..ed45511 100644
--- a/lightbox2.module
+++ b/lightbox2.module
@@ -958,6 +958,7 @@ function lightbox2_field_formatter_view($entity_type, $entity, $field, $instance
     $lightbox_style = NULL;
   }
 
+  $node_id = NULL;
   if ($entity_type == 'node') {
     $node_id = $entity->nid;
   }