diff --git a/core/includes/install.inc b/core/includes/install.inc
index bcca67ce3e5c43f53055530a66ae2a4b5e79a5a9..ec6283b7cac35794c51d19e60ed18d0779aa7f28 100644
--- a/core/includes/install.inc
+++ b/core/includes/install.inc
@@ -5,6 +5,7 @@
  * API functions for installing modules and themes.
  */
 
+use Drupal\Component\Utility\Unicode;
 use Symfony\Component\HttpFoundation\RedirectResponse;
 use Drupal\Component\Utility\Crypt;
 use Drupal\Component\Utility\OpCodeCache;
@@ -610,7 +611,7 @@ function drupal_verify_profile($install_state) {
   if (count($missing_modules)) {
     $modules = array();
     foreach ($missing_modules as $module) {
-      $modules[] = '<span class="admin-missing">' . drupal_ucfirst($module) . '</span>';
+      $modules[] = '<span class="admin-missing">' . Unicode::ucfirst($module) . '</span>';
     }
     $requirements['required_modules'] = array(
       'title'       => t('Required modules'),
diff --git a/core/modules/system/src/Tests/Module/DependencyTest.php b/core/modules/system/src/Tests/Module/DependencyTest.php
index 710341c87c3c44e875496ac4eae809c33d133223..3f537a5150f03851bc5b5e2d6fb244d6151ab266 100644
--- a/core/modules/system/src/Tests/Module/DependencyTest.php
+++ b/core/modules/system/src/Tests/Module/DependencyTest.php
@@ -6,6 +6,7 @@
  */
 
 namespace Drupal\system\Tests\Module;
+use Drupal\Component\Utility\Unicode;
 
 /**
  * Enable module without dependency enabled.
@@ -45,7 +46,7 @@ function testMissingModules() {
     // Test that the system_dependencies_test module is marked
     // as missing a dependency.
     $this->drupalGet('admin/modules');
-    $this->assertRaw(t('@module (<span class="admin-missing">missing</span>)', array('@module' => drupal_ucfirst('_missing_dependency'))), 'A module with missing dependencies is marked as such.');
+    $this->assertRaw(t('@module (<span class="admin-missing">missing</span>)', array('@module' => Unicode::ucfirst('_missing_dependency'))), 'A module with missing dependencies is marked as such.');
     $checkbox = $this->xpath('//input[@type="checkbox" and @disabled="disabled" and @name="modules[Testing][system_dependencies_test][enable]"]');
     $this->assert(count($checkbox) == 1, 'Checkbox for the module is disabled.');
   }
diff --git a/core/modules/taxonomy/taxonomy.module b/core/modules/taxonomy/taxonomy.module
index 9cc7ba268e524a2ce47568c9e4d61776caeeeac2..1c38a78bf3a59641db3c5ebe97e6df47c2cc3d12 100644
--- a/core/modules/taxonomy/taxonomy.module
+++ b/core/modules/taxonomy/taxonomy.module
@@ -6,6 +6,7 @@
  */
 
 use Drupal\Component\Utility\Tags;
+use Drupal\Component\Utility\Unicode;
 use Drupal\Core\Entity\Sql\SqlContentEntityStorage;
 use Drupal\Core\Entity\EntityInterface;
 use Drupal\Core\Form\FormStateInterface;
@@ -84,11 +85,11 @@ function taxonomy_help($route_name, RouteMatchInterface $route_match) {
       $vocabulary = $route_match->getParameter('taxonomy_vocabulary');
       switch ($vocabulary->hierarchy) {
         case TAXONOMY_HIERARCHY_DISABLED:
-          return '<p>' . t('You can reorganize the terms in %capital_name using their drag-and-drop handles, and group terms under a parent term by sliding them under and to the right of the parent.', array('%capital_name' => drupal_ucfirst($vocabulary->name), '%name' => $vocabulary->name)) . '</p>';
+          return '<p>' . t('You can reorganize the terms in %capital_name using their drag-and-drop handles, and group terms under a parent term by sliding them under and to the right of the parent.', array('%capital_name' => Unicode::ucfirst($vocabulary->name), '%name' => $vocabulary->name)) . '</p>';
         case TAXONOMY_HIERARCHY_SINGLE:
-          return '<p>' . t('%capital_name contains terms grouped under parent terms. You can reorganize the terms in %capital_name using their drag-and-drop handles.', array('%capital_name' => drupal_ucfirst($vocabulary->name), '%name' => $vocabulary->name)) . '</p>';
+          return '<p>' . t('%capital_name contains terms grouped under parent terms. You can reorganize the terms in %capital_name using their drag-and-drop handles.', array('%capital_name' => Unicode::ucfirst($vocabulary->name), '%name' => $vocabulary->name)) . '</p>';
         case TAXONOMY_HIERARCHY_MULTIPLE:
-          return '<p>' . t('%capital_name contains terms with multiple parents. Drag and drop of terms with multiple parents is not supported, but you can re-enable drag-and-drop support by editing each term to include only a single parent.', array('%capital_name' => drupal_ucfirst($vocabulary->name))) . '</p>';
+          return '<p>' . t('%capital_name contains terms with multiple parents. Drag and drop of terms with multiple parents is not supported, but you can re-enable drag-and-drop support by editing each term to include only a single parent.', array('%capital_name' => Unicode::ucfirst($vocabulary->name))) . '</p>';
       }
   }
 }