diff -u b/core/modules/system/src/Plugin/migrate/destination/d7/ThemeSettings.php b/core/modules/system/src/Plugin/migrate/destination/d7/ThemeSettings.php
--- b/core/modules/system/src/Plugin/migrate/destination/d7/ThemeSettings.php
+++ b/core/modules/system/src/Plugin/migrate/destination/d7/ThemeSettings.php
@@ -26,7 +26,7 @@
   protected $configFactory;
 
   /**
-   * Constructs a BlockedIP object.
+   * Constructs a theme settings destination object.
    *
    * @param array $configuration
    *   Plugin configuration.
diff -u b/core/modules/system/tests/src/Kernel/Plugin/migrate/source/d7/ThemeSettingsTest.php b/core/modules/system/tests/src/Kernel/Plugin/migrate/source/d7/ThemeSettingsTest.php
--- b/core/modules/system/tests/src/Kernel/Plugin/migrate/source/d7/ThemeSettingsTest.php
+++ b/core/modules/system/tests/src/Kernel/Plugin/migrate/source/d7/ThemeSettingsTest.php
@@ -25,54 +25,40 @@
     $tests = [];
 
     // The source data.
+    $value = [
+      'toggle_logo' => 1,
+      'toggle_name' => 1,
+      'toggle_slogan' => 1,
+      'toggle_node_user_picture' => 1,
+      'toggle_comment_user_picture' => 1,
+      'toggle_comment_user_verification' => 1,
+      'toggle_favicon' => 1,
+      'toggle_main_menu' => 1,
+      'toggle_secondary_menu' => 1,
+      'default_logo' => 1,
+      'logo_path' => ' ',
+      'logo_upload' => ' ',
+      'default_favicon' => 1,
+      'favicon_path' => ' ',
+      'favicon_upload' => ' ',
+      'scheme' => 'firehouse',
+    ];
+
     $tests[0]['source_data']['variable'] = [
       [
         'name' => 'theme_bartik_settings',
-        'value' => serialize([
-          'toggle_logo' => 1,
-          'toggle_name' => 1,
-          'toggle_slogan' => 1,
-          'toggle_node_user_picture' => 1,
-          'toggle_comment_user_picture' => 1,
-          'toggle_comment_user_verification' => 1,
-          'toggle_favicon' => 1,
-          'toggle_main_menu' => 1,
-          'toggle_secondary_menu' => 1,
-          'default_logo' => 1,
-          'logo_path' => ' ',
-          'logo_upload' => ' ',
-          'default_favicon' => 1,
-          'favicon_path' => ' ',
-          'favicon_upload' => ' ',
-          'scheme' => 'firehouse',
-        ]),
+        'value' => serialize($value),
       ],
     ];
 
-    // The expected results are identical to the source data.
+    // The expected results are nearly identical to the source data.
     $tests[0]['expected_data'] = [
       [
         'name' => 'theme_bartik_settings',
-        'value' => [
-          'toggle_logo' => 1,
-          'toggle_name' => 1,
-          'toggle_slogan' => 1,
-          'toggle_node_user_picture' => 1,
-          'toggle_comment_user_picture' => 1,
-          'toggle_comment_user_verification' => 1,
-          'toggle_favicon' => 1,
-          'toggle_main_menu' => 1,
-          'toggle_secondary_menu' => 1,
-          'default_logo' => 1,
-          'logo_path' => ' ',
-          'logo_upload' => ' ',
-          'default_favicon' => 1,
-          'favicon_path' => ' ',
-          'favicon_upload' => ' ',
-          'scheme' => 'firehouse',
-        ],
+        'value' => $value,
       ],
     ];
+
     return $tests;
   }