diff --git a/core/modules/filter/tests/src/Unit/FilterUninstallValidatorTest.php b/core/modules/filter/tests/src/Unit/FilterUninstallValidatorTest.php
index e9afa81..169554c 100644
--- a/core/modules/filter/tests/src/Unit/FilterUninstallValidatorTest.php
+++ b/core/modules/filter/tests/src/Unit/FilterUninstallValidatorTest.php
@@ -7,7 +7,7 @@
 
 namespace Drupal\Tests\filter\Unit;
 
-use Drupal\Component\Utility\String;
+use Drupal\Component\Utility\SafeMarkup;
 use Drupal\Tests\UnitTestCase;
 
 /**
@@ -160,7 +160,7 @@ public function testValidateNoMatchingFormats() {
       ]);
 
     $expected = [
-      String::format('Provides a filter plugin that is in use in the following filter formats: %formats.', ['%formats' => implode(', ', [
+      SafeMarkup::format('Provides a filter plugin that is in use in the following filter formats: %formats.', ['%formats' => implode(', ', [
         'Filter Format 1 Label',
         'Filter Format 2 Label',
       ])]),
diff --git a/core/modules/forum/tests/src/Unit/ForumUninstallValidatorTest.php b/core/modules/forum/tests/src/Unit/ForumUninstallValidatorTest.php
index 16549c8..b9049c5 100644
--- a/core/modules/forum/tests/src/Unit/ForumUninstallValidatorTest.php
+++ b/core/modules/forum/tests/src/Unit/ForumUninstallValidatorTest.php
@@ -7,7 +7,7 @@
 
 namespace Drupal\Tests\forum\Unit;
 
-use Drupal\Component\Utility\String;
+use Drupal\Component\Utility\SafeMarkup;
 use Drupal\Tests\UnitTestCase;
 
 /**
@@ -127,7 +127,7 @@ public function testValidateHasTermsForVocabularyWithNodesAccess() {
     $module = 'forum';
     $expected = [
       'To uninstall Forum, first delete all <em>Forum</em> content.',
-      String::format('To uninstall Forum, first delete all <a href="!url">%vocabulary</a> terms.', [
+      SafeMarkup::format('To uninstall Forum, first delete all <a href="!url">%vocabulary</a> terms.', [
         '!url' => '/path/to/vocabulary/overview',
         '%vocabulary' => 'Vocabulary label',
       ]),
@@ -164,7 +164,7 @@ public function testValidateHasTermsForVocabularyWithNodesNoAccess() {
     $module = 'forum';
     $expected = [
       'To uninstall Forum, first delete all <em>Forum</em> content.',
-      String::format('To uninstall Forum, first delete all %vocabulary terms.', [
+      SafeMarkup::format('To uninstall Forum, first delete all %vocabulary terms.', [
         '%vocabulary' => 'Vocabulary label',
       ]),
     ];
@@ -200,7 +200,7 @@ public function testValidateHasTermsForVocabularyAccess() {
 
     $module = 'forum';
     $expected = [
-      String::format('To uninstall Forum, first delete all <a href="!url">%vocabulary</a> terms.', [
+      SafeMarkup::format('To uninstall Forum, first delete all <a href="!url">%vocabulary</a> terms.', [
         '!url' => '/path/to/vocabulary/overview',
         '%vocabulary' => 'Vocabulary label',
       ]),
@@ -236,7 +236,7 @@ public function testValidateHasTermsForVocabularyNoAccess() {
 
     $module = 'forum';
     $expected = [
-      String::format('To uninstall Forum, first delete all %vocabulary terms.', [
+      SafeMarkup::format('To uninstall Forum, first delete all %vocabulary terms.', [
         '%vocabulary' => 'Vocabulary label',
       ]),
     ];
diff --git a/core/tests/Drupal/Tests/Core/Extension/RequiredModuleUninstallValidatorTest.php b/core/tests/Drupal/Tests/Core/Extension/RequiredModuleUninstallValidatorTest.php
index 6dba251..d55c141 100644
--- a/core/tests/Drupal/Tests/Core/Extension/RequiredModuleUninstallValidatorTest.php
+++ b/core/tests/Drupal/Tests/Core/Extension/RequiredModuleUninstallValidatorTest.php
@@ -7,7 +7,7 @@
 
 namespace Drupal\Tests\Core\Extension;
 
-use Drupal\Component\Utility\String;
+use Drupal\Component\Utility\SafeMarkup;
 use Drupal\Tests\UnitTestCase;
 
 /**
@@ -72,7 +72,7 @@ public function testValidateRequired() {
       ->method('getModuleInfoByModule')
       ->willReturn(['required' => TRUE, 'name' => $module]);
 
-    $expected = [String::format('The @module module is required.', ['@module' => $module])];
+    $expected = [SafeMarkup::format('The @module module is required.', ['@module' => $module])];
     $reasons = $this->uninstallValidator->validate($module);
     $this->assertSame($expected, $reasons);
   }