Error with user status value

Using http://drupal.org/project/apachesolr and http://drupal.org/project/apachesolr_user_indexer I encountered this error when registering on my site:

PDOException: SQLSTATE[HY000]: General error: 1366 Incorrect integer value: '' for column 'status' at row 1: INSERT INTO {apachesolr_index_entities_user} (entity_type, entity_id, bundle, status, changed) VALUES (:db_insert_placeholder_0, :db_insert_placeholder_1, :db_insert_placeholder_2, :db_insert_placeholder_3, :db_insert_placeholder_4); Array ( [:db_insert_placeholder_0] => user [:db_insert_placeholder_1] => 75 [:db_insert_placeholder_2] => user [:db_insert_placeholder_3] => [:db_insert_placeholder_4] => 1333416942 ) in apachesolr_entity_update() (line 1776 of drupal/sites/all/modules/apachesolr/apachesolr.module).