diff --git a/modules/system/system.api.php b/modules/system/system.api.php
index 2d16dacc5bc..051b6a49667 100644
--- a/modules/system/system.api.php
+++ b/modules/system/system.api.php
@@ -3186,6 +3186,8 @@ function hook_schema() {
  *
  * @param $schema
  *   Nested array describing the schemas for all modules.
+ *
+ * @ingroup schemaapi
  */
 function hook_schema_alter(&$schema) {
   // Add field to existing schema.