diff --git modules/field/field.crud.inc modules/field/field.crud.inc
index 400399e..9a66476 100644
--- modules/field/field.crud.inc
+++ modules/field/field.crud.inc
@@ -697,16 +697,19 @@ function field_create_instance($instance) {
 /**
  * Updates an instance of a field.
  *
- * @param $instance
+ * @param array $instance
  *   An associative array representing an instance structure. The required
  *   keys and values are:
- *     field_name: The name of an existing field.
- *     bundle: The bundle this field belongs to.
+ *   - entity_type: The type of the entity the field is attached to.
+ *   - field_name: The name of an existing field.
+ *   - bundle: The bundle this field belongs to.
  *   Read-only_id properties are assigned automatically. Any other
  *   properties specified in $instance overwrite the existing values for
  *   the instance.
+ *
  * @throw
  *   FieldException
+ *
  * @see field_create_instance()
  */
 function field_update_instance($instance) {