diff --git modules/system/system.api.php modules/system/system.api.php
index caa45c4..0d84657 100644
--- modules/system/system.api.php
+++ modules/system/system.api.php
@@ -3035,11 +3035,12 @@ function hook_query_TAG_alter(QueryAlterableInterface $query) {
  * If the module implements hook_schema(), the database tables will
  * be created before this hook is fired.
  *
- * This hook will only be called the first time a module is enabled or after it
- * is re-enabled after being uninstalled. The module's schema version will be
- * set to the module's greatest numbered update hook. Because of this, anytime a
- * hook_update_N() is added to the module, this function needs to be updated to
- * reflect the current version of the database schema.
+ * Implementations of this hook must be declared in the module's .install
+ * file. The hook will only be called the first time a module is enabled or
+ * after it is re-enabled after being uninstalled. The module's schema version
+ * will be set to the module's greatest numbered update hook. Because of this,
+ * anytime a hook_update_N() is added to the module, this function needs to be
+ * updated to reflect the current version of the database schema.
  *
  * See the Schema API documentation at
  * @link http://drupal.org/node/146843 http://drupal.org/node/146843 @endlink
@@ -3265,7 +3266,8 @@ function hook_update_last_removed() {
  * The module should not remove its entry from the {system} table. Database
  * tables defined by hook_schema() will be removed automatically.
  *
- * The uninstall hook will fire when the module gets uninstalled but before the
+ * The uninstall hook must be implemented in the module's .install file.
+ * It will fire when the module gets uninstalled but before the
  * module's database tables are removed, allowing your module to query its own
  * tables during this routine.
  *