diff --git a/core/lib/Drupal/Core/Database/Query/Select.php b/core/lib/Drupal/Core/Database/Query/Select.php
index b3426e6d4d..0b16abe9e7 100644
--- a/core/lib/Drupal/Core/Database/Query/Select.php
+++ b/core/lib/Drupal/Core/Database/Query/Select.php
@@ -128,7 +128,7 @@ class Select extends Query implements SelectInterface {
    * @param array $options
    *   Array of query options.
    */
-  public function __construct($table, $alias = NULL, Connection $connection, $options = []) {
+  public function __construct($table, $alias, Connection $connection, $options = []) {
     $options['return'] = Database::RETURN_STATEMENT;
     parent::__construct($connection, $options);
     $conjunction = isset($options['conjunction']) ? $options['conjunction'] : 'AND';
diff --git a/core/lib/Drupal/Core/Extension/ModuleHandler.php b/core/lib/Drupal/Core/Extension/ModuleHandler.php
index cfbaa61a8e..d8d36088ac 100644
--- a/core/lib/Drupal/Core/Extension/ModuleHandler.php
+++ b/core/lib/Drupal/Core/Extension/ModuleHandler.php
@@ -106,7 +106,7 @@ class ModuleHandler implements ModuleHandlerInterface {
    * @see \Drupal\Core\DrupalKernel
    * @see \Drupal\Core\CoreServiceProvider
    */
-  public function __construct($root, array $module_list = [], CacheBackendInterface $cache_backend) {
+  public function __construct($root, array $module_list, CacheBackendInterface $cache_backend) {
     $this->root = $root;
     $this->moduleList = [];
     foreach ($module_list as $name => $module) {
diff --git a/core/lib/Drupal/Core/Template/Loader/FilesystemLoader.php b/core/lib/Drupal/Core/Template/Loader/FilesystemLoader.php
index 3f727cf523..b84e790b62 100644
--- a/core/lib/Drupal/Core/Template/Loader/FilesystemLoader.php
+++ b/core/lib/Drupal/Core/Template/Loader/FilesystemLoader.php
@@ -24,7 +24,7 @@ class FilesystemLoader extends \Twig_Loader_Filesystem {
    * @param \Drupal\Core\Extension\ThemeHandlerInterface $theme_handler
    *   The theme handler service.
    */
-  public function __construct($paths = [], ModuleHandlerInterface $module_handler, ThemeHandlerInterface $theme_handler) {
+  public function __construct($paths, ModuleHandlerInterface $module_handler, ThemeHandlerInterface $theme_handler) {
     parent::__construct($paths);
 
     // Add namespaced paths for modules and themes.
diff --git a/core/modules/book/tests/src/Functional/BookTestTrait.php b/core/modules/book/tests/src/Functional/BookTestTrait.php
index f694406324..26e1613f20 100644
--- a/core/modules/book/tests/src/Functional/BookTestTrait.php
+++ b/core/modules/book/tests/src/Functional/BookTestTrait.php
@@ -72,15 +72,15 @@ public function createBook($edit = []) {
    * @param $nodes
    *   Nodes that should be in outline.
    * @param $previous
-   *   (optional) Previous link node. Defaults to FALSE.
+   *   Previous link node.
    * @param $up
-   *   (optional) Up link node. Defaults to FALSE.
+   *   Up link node.
    * @param $next
-   *   (optional) Next link node. Defaults to FALSE.
+   *   Next link node.
    * @param array $breadcrumb
    *   The nodes that should be displayed in the breadcrumb.
    */
-  public function checkBookNode(EntityInterface $node, $nodes, $previous = FALSE, $up = FALSE, $next = FALSE, array $breadcrumb) {
+  public function checkBookNode(EntityInterface $node, $nodes, $previous, $up, $next, array $breadcrumb) {
     // $number does not use drupal_static as it should not be reset
     // since it uniquely identifies each call to checkBookNode().
     static $number = 0;
diff --git a/core/phpcs.xml.dist b/core/phpcs.xml.dist
index 3945d340e5..d683c7bd6a 100644
--- a/core/phpcs.xml.dist
+++ b/core/phpcs.xml.dist
@@ -135,6 +135,7 @@
   <rule ref="PEAR.Files.IncludingFile.UseRequire">
     <severity>0</severity>
   </rule>
+  <rule ref="PEAR.Functions.ValidDefaultValue"/>
 
   <!-- PSR-2 sniffs -->
   <rule ref="PSR2.Classes.PropertyDeclaration">
diff --git a/core/tests/Drupal/Tests/Core/StringTranslation/TranslationManagerTest.php b/core/tests/Drupal/Tests/Core/StringTranslation/TranslationManagerTest.php
index 2cd750bf10..53a9241421 100644
--- a/core/tests/Drupal/Tests/Core/StringTranslation/TranslationManagerTest.php
+++ b/core/tests/Drupal/Tests/Core/StringTranslation/TranslationManagerTest.php
@@ -50,7 +50,7 @@ public function providerTestFormatPlural() {
   /**
    * @dataProvider providerTestFormatPlural
    */
-  public function testFormatPlural($count, $singular, $plural, array $args = [], array $options = [], $expected) {
+  public function testFormatPlural($count, $singular, $plural, array $args, array $options, $expected) {
     $langcode = empty($options['langcode']) ? 'fr' : $options['langcode'];
     $translator = $this->getMock('\Drupal\Core\StringTranslation\Translator\TranslatorInterface');
     $translator->expects($this->once())
@@ -78,7 +78,7 @@ public function testFormatPlural($count, $singular, $plural, array $args = [], a
    *
    * @dataProvider providerTestTranslatePlaceholder
    */
-  public function testTranslatePlaceholder($string, array $args = [], $expected_string) {
+  public function testTranslatePlaceholder($string, array $args, $expected_string) {
     $actual = $this->translationManager->translate($string, $args);
     $this->assertInstanceOf(MarkupInterface::class, $actual);
     $this->assertEquals($expected_string, (string) $actual);