diff -u b/core/modules/config_translation/src/Plugin/migrate/source/d6/I18nProfileField.php b/core/modules/config_translation/src/Plugin/migrate/source/d6/I18nProfileField.php
--- b/core/modules/config_translation/src/Plugin/migrate/source/d6/I18nProfileField.php
+++ b/core/modules/config_translation/src/Plugin/migrate/source/d6/I18nProfileField.php
@@ -3,7 +3,7 @@
 namespace Drupal\config_translation\Plugin\migrate\source\d6;
 
 @trigger_error('The ' . __NAMESPACE__ . '\I18nProfileField is deprecated in
-Drupal 8.4.0 and will be removed before Drupal 9.0.0. Instead, use 
+Drupal 8.4.0 and will be removed before Drupal 9.0.0. Instead, use
 ' . __NAMESPACE__ . '\ProfileFieldTranslation', E_USER_DEPRECATED);
 
 /**
@@ -17,6 +17,8 @@
  * @deprecated in Drupal 8.4.x and will be removed in Drupal 9.0.x. Use
  * \Drupal\config_translation\Plugin\migrate\source\d6\ProfileFieldTranslation
  * instead.
+ *
+ * @see https://www.drupal.org/node/2898649
  */
 class I18nProfileField extends ProfileFieldTranslation {
 }
reverted:
--- b/core/modules/config_translation/src/Plugin/migrate/source/d6/ProfileFieldTranslation.php
+++ /dev/null
@@ -1,53 +0,0 @@
-<?php
-
-namespace Drupal\config_translation\Plugin\migrate\source\d6;
-
-use Drupal\migrate_drupal\Plugin\migrate\source\DrupalSqlBase;
-
-/**
- * i18n strings profile field source from database.
- *
- * @MigrateSource(
- *   id = "d6_profile_field_translation",
- *   source_provider = "i18n"
- * )
- */
-class ProfileFieldTranslation extends DrupalSqlBase {
-
-  /**
-   * {@inheritdoc}
-   */
-  public function query() {
-    $query = $this->select('profile_fields', 'pf')
-      ->fields('pf', ['fid', 'name'])
-      ->fields('i18n', ['property'])
-      ->fields('lt', ['lid', 'translation', 'language']);
-    $query->leftJoin('i18n_strings', 'i18n', 'i18n.objectid = pf.name');
-    $query->leftJoin('locales_target', 'lt', 'lt.lid = i18n.lid');
-    return $query;
-  }
-
-  /**
-   * {@inheritdoc}
-   */
-  public function fields() {
-    return [
-      'fid' => $this->t('Profile field ID.'),
-      'lid' => $this->t('Locales target language ID.'),
-      'language' => $this->t('Language for this field.'),
-      'translation' => $this->t('Translation of either the title or explanation.'),
-    ];
-  }
-
-  /**
-   * {@inheritdoc}
-   */
-  public function getIds() {
-    $ids['fid']['type'] = 'integer';
-    $ids['language']['type'] = 'string';
-    $ids['lid']['type'] = 'integer';
-    $ids['lid']['alias'] = 'lt';
-    return $ids;
-  }
-
-}
reverted:
--- b/core/modules/migrate_drupal/src/Plugin/migrate/source/d6/VariableTranslation.php
+++ /dev/null
@@ -1,100 +0,0 @@
-<?php
-
-namespace Drupal\migrate_drupal\Plugin\migrate\source\d6;
-
-use Drupal\Core\Entity\EntityManagerInterface;
-use Drupal\Core\State\StateInterface;
-use Drupal\migrate\Plugin\MigrationInterface;
-use Drupal\migrate_drupal\Plugin\migrate\source\DrupalSqlBase;
-
-/**
- * Drupal i18n_variable source from database.
- *
- * @MigrateSource(
- *   id = "variable_translation"
- * )
- */
-class VariableTranslation extends DrupalSqlBase {
-
-  /**
-   * The variable names to fetch.
-   *
-   * @var array
-   */
-  protected $variables;
-
-  /**
-   * {@inheritdoc}
-   */
-  public function __construct(array $configuration, $plugin_id, $plugin_definition, MigrationInterface $migration, StateInterface $state, EntityManagerInterface $entity_manager) {
-    parent::__construct($configuration, $plugin_id, $plugin_definition, $migration, $state, $entity_manager);
-    $this->variables = $this->configuration['variables'];
-  }
-
-  /**
-   * {@inheritdoc}
-   */
-  protected function initializeIterator() {
-    return new \ArrayIterator($this->values());
-  }
-
-  /**
-   * Return the values of the variables specified in the plugin configuration.
-   *
-   * @return array
-   *   An associative array where the keys are the variables specified in the
-   *   plugin configuration and the values are the values found in the source.
-   *   A key/value pair is added for the language code. Only those values are
-   *   returned that are actually in the database.
-   */
-  protected function values() {
-    $values = [];
-    $result = $this->prepareQuery()->execute()->FetchAllAssoc('language');
-    foreach ($result as $i18n_variable) {
-      $values[]['language'] = $i18n_variable->language;
-    }
-    $result = $this->prepareQuery()->execute()->FetchAll();
-    foreach ($result as $i18n_variable) {
-      foreach ($values as $key => $value) {
-        if ($values[$key]['language'] === $i18n_variable->language) {
-          $values[$key][$i18n_variable->name] = unserialize($i18n_variable->value);
-          break;
-        }
-      }
-    }
-    return $values;
-  }
-
-  /**
-   * {@inheritdoc}
-   */
-  public function count() {
-    return $this->initializeIterator()->count();
-  }
-
-  /**
-   * {@inheritdoc}
-   */
-  public function fields() {
-    return array_combine($this->variables, $this->variables);
-  }
-
-  /**
-   * {@inheritdoc}
-   */
-  public function query() {
-    return $this->getDatabase()
-      ->select('i18n_variable', 'v')
-      ->fields('v')
-      ->condition('name', (array) $this->configuration['variables'], 'IN');
-  }
-
-  /**
-   * {@inheritdoc}
-   */
-  public function getIds() {
-    $ids['language']['type'] = 'string';
-    return $ids;
-  }
-
-}
diff -u b/core/modules/migrate_drupal/src/Plugin/migrate/source/d6/i18nVariable.php b/core/modules/migrate_drupal/src/Plugin/migrate/source/d6/VariableTranslation.php
--- b/core/modules/migrate_drupal/src/Plugin/migrate/source/d6/i18nVariable.php
+++ b/core/modules/migrate_drupal/src/Plugin/migrate/source/d6/VariableTranslation.php
@@ -4,17 +4,97 @@
 
-@trigger_error('The ' . __NAMESPACE__ . '\i18nVariable is deprecated in
-Drupal 8.4.0 and will be removed before Drupal 9.0.0. Instead, use 
-' . __NAMESPACE__ . '\VariableTranslation', E_USER_DEPRECATED);
+use Drupal\Core\Entity\EntityManagerInterface;
+use Drupal\Core\State\StateInterface;
+use Drupal\migrate\Plugin\MigrationInterface;
+use Drupal\migrate_drupal\Plugin\migrate\source\DrupalSqlBase;
 
 /**
  * Drupal i18n_variable source from database.
  *
  * @MigrateSource(
- *   id = "i18n_variable"
+ *   id = "variable_translation"
  * )
- *
- * @deprecated in Drupal 8.4.x and will be removed in Drupal 9.0.x. Use
- * \Drupal\migrate_drupal\Plugin\migrate\source\d6\VariableTranslation instead.
  */
-class i18nVariable extends VariableTranslation {
+class VariableTranslation extends DrupalSqlBase {
+
+  /**
+   * The variable names to fetch.
+   *
+   * @var array
+   */
+  protected $variables;
+
+  /**
+   * {@inheritdoc}
+   */
+  public function __construct(array $configuration, $plugin_id, $plugin_definition, MigrationInterface $migration, StateInterface $state, EntityManagerInterface $entity_manager) {
+    parent::__construct($configuration, $plugin_id, $plugin_definition, $migration, $state, $entity_manager);
+    $this->variables = $this->configuration['variables'];
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function initializeIterator() {
+    return new \ArrayIterator($this->values());
+  }
+
+  /**
+   * Return the values of the variables specified in the plugin configuration.
+   *
+   * @return array
+   *   An associative array where the keys are the variables specified in the
+   *   plugin configuration and the values are the values found in the source.
+   *   A key/value pair is added for the language code. Only those values are
+   *   returned that are actually in the database.
+   */
+  protected function values() {
+    $values = [];
+    $result = $this->prepareQuery()->execute()->FetchAllAssoc('language');
+    foreach ($result as $i18n_variable) {
+      $values[]['language'] = $i18n_variable->language;
+    }
+    $result = $this->prepareQuery()->execute()->FetchAll();
+    foreach ($result as $i18n_variable) {
+      foreach ($values as $key => $value) {
+        if ($values[$key]['language'] === $i18n_variable->language) {
+          $values[$key][$i18n_variable->name] = unserialize($i18n_variable->value);
+          break;
+        }
+      }
+    }
+    return $values;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function count() {
+    return $this->initializeIterator()->count();
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function fields() {
+    return array_combine($this->variables, $this->variables);
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function query() {
+    return $this->getDatabase()
+      ->select('i18n_variable', 'v')
+      ->fields('v')
+      ->condition('name', (array) $this->configuration['variables'], 'IN');
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getIds() {
+    $ids['language']['type'] = 'string';
+    return $ids;
+  }
+
 }
reverted:
--- b/core/modules/migrate_drupal/tests/src/Unit/source/d6/VariableTranslationTest.php
+++ a/core/modules/migrate_drupal/tests/src/Unit/source/d6/i18nVariableTest.php
@@ -9,11 +9,11 @@
  *
  * @group migrate_drupal
  */
+class i18nVariableTest extends MigrateSqlSourceTestCase {
-class VariableTranslationTest extends MigrateSqlSourceTestCase {
 
   // The plugin system is not working during unit testing so the source plugin
   // class needs to be manually specified.
+  const PLUGIN_CLASS = 'Drupal\migrate_drupal\Plugin\migrate\source\d6\i18nVariable';
-  const PLUGIN_CLASS = 'Drupal\migrate_drupal\Plugin\migrate\source\d6\VariableTranslation';
 
   /**
    * Define bare minimum migration configuration.
@@ -22,7 +22,7 @@
     'id' => 'test',
     'highWaterProperty' => ['field' => 'test'],
     'source' => [
+      'plugin' => 'i18n_variable',
-      'plugin' => 'variable_translation',
       'variables' => [
         'site_slogan',
         'site_name',
only in patch2:
unchanged:
--- /dev/null
+++ b/core/modules/config_translation/tests/src/Kernel/Plugin/migrate/source/d6/ProfileFieldTranslationTest.php
@@ -0,0 +1,79 @@
+<?php
+
+namespace Drupal\Tests\config_translation\Kernel\Plugin\migrate\source\d6;
+
+use Drupal\Tests\migrate\Kernel\MigrateSqlSourceTestBase;
+
+/**
+ * Tests the i18nProfileField source plugin.
+ *
+ * @covers \Drupal\config_translation\Plugin\migrate\source\d6\ProfileFieldTranslation
+ * @group migrate_drupal
+ */
+class ProfileFieldTranslationTest extends MigrateSqlSourceTestBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  public static $modules = ['config_translation', 'migrate_drupal', 'user'];
+
+  /**
+   * {@inheritdoc}
+   */
+  public function providerSource() {
+    $test = [];
+    $test[0]['source_data'] = [
+      'profile_fields' => [
+        [
+          'fid' => 42,
+          'title' => 'I love migrations',
+          'name' => 'profile_love_migrations',
+        ],
+      ],
+      'i18n_strings' => [
+        [
+          'lid' => 10,
+          'objectid' => 'profile_love_migrations',
+          'type' => 'field',
+          'property' => 'title',
+        ],
+        [
+          'lid' => 11,
+          'objectid' => 'profile_love_migrations',
+          'type' => 'field',
+          'property' => 'explanation'
+        ]
+      ],
+      'locales_target' => [
+        [
+          'lid' => 10,
+          'translation' => "J'aime les migrations.",
+          'language' => 'fr',
+        ],
+        [
+          'lid' => 11,
+          'translation' => 'Si vous cochez cette case, vous aimez les migrations.',
+          'language' => 'fr',
+        ],
+      ],
+    ];
+    $test[0]['expected_results'] = [
+      [
+        'property' => 'title',
+        'translation' => "J'aime les migrations.",
+        'language' => 'fr',
+        'fid' => '42',
+        'name' => 'profile_love_migrations',
+      ],
+      [
+        'property' => 'explanation',
+        'translation' => 'Si vous cochez cette case, vous aimez les migrations.',
+        'language' => 'fr',
+        'fid' => '42',
+        'name' => 'profile_love_migrations',
+      ],
+    ];
+    return $test;
+  }
+
+}
only in patch2:
unchanged:
--- /dev/null
+++ b/core/modules/migrate_drupal/tests/src/Unit/source/d6/VariableTranslationTest.php
@@ -0,0 +1,61 @@
+<?php
+
+namespace Drupal\Tests\migrate_drupal\Unit\source\d6;
+
+use Drupal\Tests\migrate\Unit\MigrateSqlSourceTestCase;
+
+/**
+ * Tests the variable source plugin.
+ *
+ * @group migrate_drupal
+ */
+class VariableTranslationTest extends MigrateSqlSourceTestCase {
+
+  // The plugin system is not working during unit testing so the source plugin
+  // class needs to be manually specified.
+  const PLUGIN_CLASS = 'Drupal\migrate_drupal\Plugin\migrate\source\d6\VariableTranslation';
+
+  /**
+   * Define bare minimum migration configuration.
+   */
+  protected $migrationConfiguration = [
+    'id' => 'test',
+    'highWaterProperty' => ['field' => 'test'],
+    'source' => [
+      'plugin' => 'variable_translation',
+      'variables' => [
+        'site_slogan',
+        'site_name',
+      ],
+    ],
+  ];
+
+  /**
+   * Expected results from the source.
+   */
+  protected $expectedResults = [
+    [
+      'language' => 'fr',
+      'site_slogan' => 'Migrate est génial',
+      'site_name' => 'nom de site',
+    ],
+    [
+      'language' => 'mi',
+      'site_slogan' => 'Ko whakamataku heke',
+      'site_name' => 'ingoa_pae',
+    ]
+  ];
+
+  /**
+   * Database contents for tests.
+   */
+  protected $databaseContents = [
+    'i18n_variable' => [
+      ['name' => 'site_slogan', 'language' => 'fr', 'value' => 's:19:"Migrate est génial";'],
+      ['name' => 'site_name', 'language' => 'fr', 'value' => 's:11:"nom de site";'],
+      ['name' => 'site_slogan', 'language' => 'mi', 'value' => 's:19:"Ko whakamataku heke";'],
+      ['name' => 'site_name', 'language' => 'mi', 'value' => 's:9:"ingoa_pae";'],
+    ],
+  ];
+
+}