diff --git sites/default/modules/contrib/user_activity/user_activity.install sites/default/modules/contrib/user_activity/user_activity.install
index 22bf8bf..71c3ed6 100644
--- user_activity.install
+++ user_activity.install
@@ -76,6 +76,8 @@ function user_activity_schema() {
       'uid' => array('uid'),
     ),
   );
+  $schema['cache_user_activity'] = drupal_get_schema_unprocessed('system', 'cache');
+
   return $schema;
 }
 
@@ -165,3 +167,14 @@ function user_activity_migrate_6101() {
   }
   $context['message'] = t('Migrated user activity indexes.');
 }
+
+/**
+ * Add the cache table.
+ */
+function user_activity_update_6102() {
+  $ret = array();
+  $schema = user_activity_schema();
+  db_create_table($ret, 'cache_user_activity', $schema['cache_user_activity']);
+
+  return $ret;
+}