diff --git a/field_permissions.api.php b/field_permissions.api.php
new file mode 100644
index 0000000..87cb49b
--- /dev/null
+++ b/field_permissions.api.php
@@ -0,0 +1,22 @@
+<?php
+
+/**
+ * @file
+ * Hooks provided by the Field Permission module.
+ */
+
+/**
+ * Defines the owner of an entity.
+ *
+ * Because not all entities have uids, this hook allows other modules to specify
+ * one.
+ *
+ * @param int $uid
+ *   The userid that will be checked against the current user's account->uid.
+ * @param object $entity
+ *   The entity this field belongs to.
+ */
+function hook_field_permissions_userid_ENTITY_TYPE_alter(&$uid, $entity) {
+  // This example always assigns user 15 as the owner of an entity.
+  $uid = 15;
+}
diff --git a/field_permissions.module b/field_permissions.module
index bc4d1f5..5e4ab56 100644
--- a/field_permissions.module
+++ b/field_permissions.module
@@ -258,5 +258,10 @@ function _field_permissions_entity_is_owned_by_account($entity, $account) {
   // set (for example, if the entity type does not store a uid or does not have
   // a concept of "ownership"), we need to assume that the provided user
   // account does not own it.
-  return isset($entity->uid) && $entity->uid == $account->uid;
+  $uid = isset($entity->uid) ? $entity->uid : FALSE;
+  if(method_exists($entity, 'entityType')) {
+    drupal_alter('field_permissions_userid_' . $entity->entityType(), $uid, $entity);
+  }
+
+  return $uid == $account->uid;
 }