diff --git a/core/includes/file.inc b/core/includes/file.inc
index 545fca3..815afdc 100644
--- a/core/includes/file.inc
+++ b/core/includes/file.inc
@@ -1309,17 +1309,14 @@ function file_get_mimetype($uri, $mapping = NULL) {
  */
 function drupal_chmod($uri, $mode = NULL) {
   if (!isset($mode)) {
-    // Configuration system stores default modes as strings. We use octdec() so
-    // that the octal permission numbers can be expressed as integers or strings
-    // and will be converted correctly in both cases.
     if (is_dir($uri)) {
-      $mode = octdec(\Drupal::config('system.file')->get('chmod.directory'));
+      $mode = \Drupal::config('system.file')->get('chmod.directory');
       if (!$mode) {
         $mode = 0775;
       }
     }
     else {
-      $mode = octdec(\Drupal::config('system.file')->get('chmod.file'));
+      $mode = \Drupal::config('system.file')->get('chmod.file');
       if (!$mode) {
         $mode = 0664;
       }
@@ -1497,7 +1494,7 @@ function drupal_mkdir($uri, $mode = NULL, $recursive = FALSE, $context = NULL) {
     $mode = FALSE;
     // During early update there's no container.
     if (is_object(\Drupal::getContainer())) {
-      $mode = octdec(\Drupal::config('system.file')->get('chmod.directory'));
+      $mode = \Drupal::config('system.file')->get('chmod.directory');
     }
     if (!$mode) {
       $mode = 0775;
diff --git a/core/modules/system/config/system.date.yml b/core/modules/system/config/system.date.yml
index 29889df..6470af2 100644
--- a/core/modules/system/config/system.date.yml
+++ b/core/modules/system/config/system.date.yml
@@ -4,6 +4,6 @@ first_day: 0
 timezone:
   default: ''
   user:
-    configurable: '1'
-    warn: '0'
-    default: '0'
+    configurable: true
+    warn: false
+    default: 0
diff --git a/core/modules/system/config/system.file.yml b/core/modules/system/config/system.file.yml
index b5be48c..5d3ae38 100644
--- a/core/modules/system/config/system.file.yml
+++ b/core/modules/system/config/system.file.yml
@@ -1,8 +1,8 @@
-allow_insecure_uploads: '0'
+allow_insecure_uploads: false
 # chmod variables should be a string in PHP Octal Notation.
 chmod:
-  directory: '0775'
-  file: '0664'
+  directory: 0775
+  file: 0664
 default_scheme: 'public'
 path:
   private: ''
diff --git a/core/modules/system/config/system.image.gd.yml b/core/modules/system/config/system.image.gd.yml
index fbc379f..342e071 100644
--- a/core/modules/system/config/system.image.gd.yml
+++ b/core/modules/system/config/system.image.gd.yml
@@ -1 +1 @@
-jpeg_quality: '75'
+jpeg_quality: 75
diff --git a/core/modules/system/config/system.module.yml b/core/modules/system/config/system.module.yml
index 696bedc..9ec80e1 100644
--- a/core/modules/system/config/system.module.yml
+++ b/core/modules/system/config/system.module.yml
@@ -1,2 +1,2 @@
 enabled:
-  system: '0'
+  system: 0
diff --git a/core/modules/system/config/system.performance.yml b/core/modules/system/config/system.performance.yml
index 67e82cf..9957bef 100644
--- a/core/modules/system/config/system.performance.yml
+++ b/core/modules/system/config/system.performance.yml
@@ -1,6 +1,6 @@
 cache:
   page:
-    use_internal: '0'
+    use_internal: false
     max_age: 0
 css:
   preprocess: false
diff --git a/core/modules/system/config/system.theme.global.yml b/core/modules/system/config/system.theme.global.yml
index 2d5bc35..13036bf 100644
--- a/core/modules/system/config/system.theme.global.yml
+++ b/core/modules/system/config/system.theme.global.yml
@@ -2,18 +2,18 @@ favicon:
   mimetype: image/vnd.microsoft.icon
   path: ''
   url: ''
-  use_default: '1'
+  use_default: true
 features:
-  comment_user_picture: '1'
-  comment_user_verification: '1'
-  favicon: '1'
-  logo: '1'
-  name: '1'
-  node_user_picture: '1'
-  main_menu: '1'
-  secondary_menu: '1'
-  slogan: '1'
+  comment_user_picture: true
+  comment_user_verification: true
+  favicon: true
+  logo: true
+  name: true
+  node_user_picture: true
+  main_menu: true
+  secondary_menu: true
+  slogan: true
 logo:
   path: ''
   url: ''
-  use_default: '1'
+  use_default: true
diff --git a/core/modules/system/config/system.theme.yml b/core/modules/system/config/system.theme.yml
index c56c7f2..e88d701 100644
--- a/core/modules/system/config/system.theme.yml
+++ b/core/modules/system/config/system.theme.yml
@@ -1,4 +1,4 @@
-admin: '0'
+admin: ''
 enabled:
-  stark: '0'
+  stark: 0
 default: stark
diff --git a/core/modules/system/lib/Drupal/system/Tests/File/DirectoryTest.php b/core/modules/system/lib/Drupal/system/Tests/File/DirectoryTest.php
index 7fd19c5..eef3373 100644
--- a/core/modules/system/lib/Drupal/system/Tests/File/DirectoryTest.php
+++ b/core/modules/system/lib/Drupal/system/Tests/File/DirectoryTest.php
@@ -89,7 +89,7 @@ function testFileCheckDirectoryHandling() {
     }
 
     // Test that the directory has the correct permissions.
-    $this->assertDirectoryPermissions($directory, octdec(\Drupal::config('system.file')->get('chmod.directory')));
+    $this->assertDirectoryPermissions($directory, \Drupal::config('system.file')->get('chmod.directory'));
 
     // Remove .htaccess file to then test that it gets re-created.
     @drupal_unlink(file_default_scheme() . '://.htaccess');
diff --git a/core/modules/system/lib/Drupal/system/Tests/File/FileTestBase.php b/core/modules/system/lib/Drupal/system/Tests/File/FileTestBase.php
index 540c19a..30973ad 100644
--- a/core/modules/system/lib/Drupal/system/Tests/File/FileTestBase.php
+++ b/core/modules/system/lib/Drupal/system/Tests/File/FileTestBase.php
@@ -82,11 +82,6 @@ function assertSameFile(FileInterface $file1, FileInterface $file2) {
    *   Optional message.
    */
   function assertFilePermissions($filepath, $expected_mode, $message = NULL) {
-    // Configuration system stores default modes as strings.
-    if (is_string($expected_mode)) {
-      // Convert string to octal.
-      $expected_mode = octdec($expected_mode);
-    }
     // Clear out PHP's file stat cache to be sure we see the current value.
     clearstatcache(TRUE, $filepath);
 
@@ -122,11 +117,6 @@ function assertFilePermissions($filepath, $expected_mode, $message = NULL) {
    *   Optional message.
    */
   function assertDirectoryPermissions($directory, $expected_mode, $message = NULL) {
-    // Configuration system stores default modes as strings.
-    if (is_string($expected_mode)) {
-      // Convert string to octal.
-      $expected_mode = octdec($expected_mode);
-    }
     // Clear out PHP's file stat cache to be sure we see the current value.
     clearstatcache(TRUE, $directory);
 
diff --git a/core/modules/system/lib/Drupal/system/Tests/File/UnmanagedCopyTest.php b/core/modules/system/lib/Drupal/system/Tests/File/UnmanagedCopyTest.php
index 70f1903..b9e4308 100644
--- a/core/modules/system/lib/Drupal/system/Tests/File/UnmanagedCopyTest.php
+++ b/core/modules/system/lib/Drupal/system/Tests/File/UnmanagedCopyTest.php
@@ -34,7 +34,7 @@ function testNormal() {
     $this->assertEqual($new_filepath, $desired_filepath, 'Returned expected filepath.');
     $this->assertTrue(file_exists($uri), 'Original file remains.');
     $this->assertTrue(file_exists($new_filepath), 'New file exists.');
-    $this->assertFilePermissions($new_filepath, octdec($config->get('chmod.file')));
+    $this->assertFilePermissions($new_filepath, $config->get('chmod.file'));
 
     // Copying with rename.
     $desired_filepath = 'public://' . $this->randomName();
@@ -44,7 +44,7 @@ function testNormal() {
     $this->assertNotEqual($newer_filepath, $desired_filepath, 'Returned expected filepath.');
     $this->assertTrue(file_exists($uri), 'Original file remains.');
     $this->assertTrue(file_exists($newer_filepath), 'New file exists.');
-    $this->assertFilePermissions($newer_filepath, octdec($config->get('chmod.file')));
+    $this->assertFilePermissions($newer_filepath, $config->get('chmod.file'));
 
     // TODO: test copying to a directory (rather than full directory/file path)
     // TODO: test copying normal files using normal paths (rather than only streams)
@@ -75,7 +75,7 @@ function testOverwriteSelf() {
     $this->assertNotEqual($new_filepath, $uri, 'Copied file has a new name.');
     $this->assertTrue(file_exists($uri), 'Original file exists after copying onto itself.');
     $this->assertTrue(file_exists($new_filepath), 'Copied file exists after copying onto itself.');
-    $this->assertFilePermissions($new_filepath, octdec($config->get('chmod.file')));
+    $this->assertFilePermissions($new_filepath, $config->get('chmod.file'));
 
     // Copy the file onto itself without renaming fails.
     $new_filepath = file_unmanaged_copy($uri, $uri, FILE_EXISTS_ERROR);
@@ -93,6 +93,6 @@ function testOverwriteSelf() {
     $this->assertNotEqual($new_filepath, $uri, 'Copied file has a new name.');
     $this->assertTrue(file_exists($uri), 'Original file exists after copying onto itself.');
     $this->assertTrue(file_exists($new_filepath), 'Copied file exists after copying onto itself.');
-    $this->assertFilePermissions($new_filepath, octdec($config->get('chmod.file')));
+    $this->assertFilePermissions($new_filepath, $config->get('chmod.file'));
   }
 }
diff --git a/core/modules/system/lib/Drupal/system/Tests/File/UnmanagedMoveTest.php b/core/modules/system/lib/Drupal/system/Tests/File/UnmanagedMoveTest.php
index 1503bd1..5901a9d 100644
--- a/core/modules/system/lib/Drupal/system/Tests/File/UnmanagedMoveTest.php
+++ b/core/modules/system/lib/Drupal/system/Tests/File/UnmanagedMoveTest.php
@@ -34,7 +34,7 @@ function testNormal() {
     $this->assertEqual($new_filepath, $desired_filepath, 'Returned expected filepath.');
     $this->assertTrue(file_exists($new_filepath), 'File exists at the new location.');
     $this->assertFalse(file_exists($uri), 'No file remains at the old location.');
-    $this->assertFilePermissions($new_filepath, octdec($config->get('chmod.file')));
+    $this->assertFilePermissions($new_filepath, $config->get('chmod.file'));
 
     // Moving with rename.
     $desired_filepath = 'public://' . $this->randomName();
@@ -45,7 +45,7 @@ function testNormal() {
     $this->assertNotEqual($newer_filepath, $desired_filepath, 'Returned expected filepath.');
     $this->assertTrue(file_exists($newer_filepath), 'File exists at the new location.');
     $this->assertFalse(file_exists($new_filepath), 'No file remains at the old location.');
-    $this->assertFilePermissions($newer_filepath, octdec($config->get('chmod.file')));
+    $this->assertFilePermissions($newer_filepath, $config->get('chmod.file'));
 
     // TODO: test moving to a directory (rather than full directory/file path)
     // TODO: test creating and moving normal files (rather than streams)
diff --git a/core/modules/system/lib/Drupal/system/Tests/File/UnmanagedSaveDataTest.php b/core/modules/system/lib/Drupal/system/Tests/File/UnmanagedSaveDataTest.php
index 043ed6c..1b03d13 100644
--- a/core/modules/system/lib/Drupal/system/Tests/File/UnmanagedSaveDataTest.php
+++ b/core/modules/system/lib/Drupal/system/Tests/File/UnmanagedSaveDataTest.php
@@ -36,6 +36,6 @@ function testFileSaveData() {
     $this->assertTrue($filepath, 'Unnamed file saved correctly.');
     $this->assertEqual('asdf.txt', drupal_basename($filepath), 'File was named correctly.');
     $this->assertEqual($contents, file_get_contents($filepath), 'Contents of the file are correct.');
-    $this->assertFilePermissions($filepath, octdec(\Drupal::config('system.file')->get('chmod.file')));
+    $this->assertFilePermissions($filepath, \Drupal::config('system.file')->get('chmod.file'));
   }
 }
diff --git a/core/modules/system/tests/modules/entity_test/config/entity.view_mode.entity_test.full.yml b/core/modules/system/tests/modules/entity_test/config/entity.view_mode.entity_test.full.yml
index cb44396..412942c 100644
--- a/core/modules/system/tests/modules/entity_test/config/entity.view_mode.entity_test.full.yml
+++ b/core/modules/system/tests/modules/entity_test/config/entity.view_mode.entity_test.full.yml
@@ -1,5 +1,5 @@
 id: entity_test.full
 label: Full
-status: '0'
-cache: '1'
+status: false
+cache: true
 targetEntityType: entity_test
diff --git a/core/modules/system/tests/modules/entity_test/config/entity.view_mode.entity_test.test.yml b/core/modules/system/tests/modules/entity_test/config/entity.view_mode.entity_test.test.yml
index aa9b27e..baeed36 100644
--- a/core/modules/system/tests/modules/entity_test/config/entity.view_mode.entity_test.test.yml
+++ b/core/modules/system/tests/modules/entity_test/config/entity.view_mode.entity_test.test.yml
@@ -1,5 +1,5 @@
 id: entity_test.test
 label: Test
-status: '0'
-cache: '0'
+status: false
+cache: false
 targetEntityType: entity_test
diff --git a/core/modules/system/tests/modules/update_script_test/config/update_script_test.settings.yml b/core/modules/system/tests/modules/update_script_test/config/update_script_test.settings.yml
index e0be69e..0c4e667 100644
--- a/core/modules/system/tests/modules/update_script_test/config/update_script_test.settings.yml
+++ b/core/modules/system/tests/modules/update_script_test/config/update_script_test.settings.yml
@@ -1 +1 @@
-requirement_type: '0'
+requirement_type: 0