diff --git a/entityreference_prepopulate.module b/entityreference_prepopulate.module
index 2a25682..90a01a2 100644
--- a/entityreference_prepopulate.module
+++ b/entityreference_prepopulate.module
@@ -67,7 +67,7 @@ function entityreference_prepopulate_field_default_value($entity_type, $entity,
  * Default value callback for Organic groups; Filter results by field-mode.
  */
 function entityreference_prepopulate_og_field_default_value($entity_type, $entity, $field, $instance, $langcode) {
-  if (empty($instance['field_mode'])) {
+  if (isset($instance['field_mode']) && empty($instance['field_mode'])) {
     return;
   }
   if ($items = entityreference_prepopulate_get_values($field, $instance)) {