diff --git a/core/includes/update.inc b/core/includes/update.inc
index 1660d7dbb6ecafdead32c46161a09f165ca9270c..7a4a27d194632c89b2a7882fd1adaddf8230357d 100644
--- a/core/includes/update.inc
+++ b/core/includes/update.inc
@@ -851,23 +851,23 @@ function update_retrieve_dependencies() {
 
 /**
  * Updates config with values set on Drupal 7.x
- * 
+ *
  * Provide a generalised method to migrate variables from Drupal 7 to Drupal 8's
  * configuration management system.
  *
  * @param $config_name
  *   The name of the configuration object to retrieve. The name corresponds to
- *   an XML configuration file. For @code config(book.admin) @endcode, the
- *   config object returned will contain the contents of book.admin.xml.
+ *   an XML configuration file. For example, passing "book.admin" will return
+ *   the config object containing the contents of book.admin.xml.
  * @param $variable_map
  *   An array to map new to old configuration naming conventions. Example:
  *   @code
  *     array('new_config' => 'old_config')
- *   @endcode 
- *   This would update the value for new_config to the value old_config has in 
+ *   @endcode
+ *   This would update the value for new_config to the value old_config has in
  *   the variable table.
  */
-function update_variables_to_config($config_name, $variable_map = array()) {
+function update_variables_to_config($config_name, array $variable_map = array()) {
   $config = config($config_name);
   $config_data = array_keys($config->get());
 
diff --git a/core/modules/config/config.test b/core/modules/config/config.test
index 34f536aa831ca772ce0017b0186b99d4434780d2..a164108c3d57fca47bb7a435552ea7acfca443ae 100644
--- a/core/modules/config/config.test
+++ b/core/modules/config/config.test
@@ -306,7 +306,7 @@ class ConfUpdate7to8TestCase extends DrupalWebTestCase {
   public static function getInfo() {
     return array(
       'name' => 'Configuration update from Drupal 7 to 8',
-      'description' => 'Tests the ability to update Drupal 7 variables to the 
+      'description' => 'Tests the ability to update Drupal 7 variables to the
         configuration management system.',
       'group' => 'Configuration',
     );
@@ -329,7 +329,7 @@ class ConfUpdate7to8TestCase extends DrupalWebTestCase {
 
     update_variables_to_config('config.test', array('config_test_bar' => 'config_bar'));
     $config = config('config.test');
-    $this->assertEqual($config->get('config_test_foo'), $this->testContent); 
-    $this->assertEqual($config->get('config_test_bar'), $this->testContent); 
+    $this->assertEqual($config->get('config_test_foo'), $this->testContent);
+    $this->assertEqual($config->get('config_test_bar'), $this->testContent);
   }
 }