diff --git a/modules/file/file.field.inc b/modules/file/file.field.inc
index b26d7e4..794f16e 100644
--- a/modules/file/file.field.inc
+++ b/modules/file/file.field.inc
@@ -252,6 +252,12 @@ function file_field_insert($entity_type, $entity, $field, $instance, $langcode,
  * Checks for files that have been removed from the object.
  */
 function file_field_update($entity_type, $entity, $field, $instance, $langcode, &$items) {
+  // Check whether the field is defined on the object.
+  if (!isset($entity->{$field['field_name']})) {
+    // We cannot check for removed files if the field is not defined.
+    return;
+  }
+
   list($id, $vid, $bundle) = entity_extract_ids($entity_type, $entity);
 
   // On new revisions, all files are considered to be a new usage and no