diff --git a/core/lib/Drupal/Core/Database/Query/ExtendableInterface.php b/core/lib/Drupal/Core/Database/Query/ExtendableInterface.php
index b0d6f76..d512bd6 100644
--- a/core/lib/Drupal/Core/Database/Query/ExtendableInterface.php
+++ b/core/lib/Drupal/Core/Database/Query/ExtendableInterface.php
@@ -6,11 +6,11 @@
  * Interface for extendable query objects.
  *
  * "Extenders" follow the "Decorator" OOP design pattern.  That is, they wrap
- * and "decorate" another object.  In our case, they implement the same interface
- * as select queries and wrap a select query, to which they delegate almost all
- * operations.  Subclasses of this class may implement additional methods or
- * override existing methods as appropriate.  Extenders may also wrap other
- * extender objects, allowing for arbitrarily complex "enhanced" queries.
+ * and "decorate" another object. In our case, they implement the same
+ * interface as select queries and wrap a select query, to which they delegate
+ * almost all operations. Subclasses of this class may implement additional
+ * methods or override existing methods as appropriate. Extenders may also wrap
+ * other extender objects, allowing for arbitrarily complex "enhanced" queries.
  */
 interface ExtendableInterface {
 
@@ -18,9 +18,12 @@
    * Enhance this object by wrapping it in an extender object.
    *
    * @param $extender_name
-   *   The base name of the extending class.  The base name will be checked
-   *   against the current database connection to allow driver-specific subclasses
-   *   as well, using the same logic as the query objects themselves.
+   *   The fully-qualified name of the extender class, without the leading '\'
+   *   (for example, Drupal\my_module\myExtenderClass). The extender name will
+   *   be checked against the current database connection to allow
+   *   driver-specific subclasses as well, using the same logic as the query
+   *   objects themselves.
+   *
    * @return \Drupal\Core\Database\Query\ExtendableInterface
    *   The extender object, which now contains a reference to this object.
    */