diff --git a/core/modules/config_translation/src/FormElement/FormElementBase.php b/core/modules/config_translation/src/FormElement/FormElementBase.php
index e13cc31..7db01e1 100644
--- a/core/modules/config_translation/src/FormElement/FormElementBase.php
+++ b/core/modules/config_translation/src/FormElement/FormElementBase.php
@@ -91,7 +91,6 @@ public function getTranslationBuild(LanguageInterface $source_language, Language
    *   A render array for the source value.
    */
   protected function getSourceElement(LanguageInterface $source_language, $source_config) {
-    // @todo Should support singular+plurals https://www.drupal.org/node/2454829
     if ($source_config) {
       $value = '<span lang="' . $source_language->getId() . '">' . nl2br($source_config) . '</span>';
     }
@@ -162,7 +161,6 @@ protected function getSourceElement(LanguageInterface $source_language, $source_
    */
   protected function getTranslationElement(LanguageInterface $translation_language, $source_config, $translation_config) {
     // Add basic properties that apply to all form elements.
-    // @todo Should support singular+plurals https://www.drupal.org/node/2454829
     return array(
       '#title' => $this->t('!label <span class="visually-hidden">(!source_language)</span>', array(
         '!label' => $this->t($this->definition['label']),
diff --git a/core/modules/config_translation/src/FormElement/PluralString.php b/core/modules/config_translation/src/FormElement/PluralString.php
index da216ee..15d88dc 100644
--- a/core/modules/config_translation/src/FormElement/PluralString.php
+++ b/core/modules/config_translation/src/FormElement/PluralString.php
@@ -7,12 +7,14 @@
 
 namespace Drupal\config_translation\FormElement;
 
+use Drupal\Component\Utility\SafeMarkup;
 use Drupal\Core\Config\Config;
 use Drupal\Core\Language\LanguageInterface;
 use Drupal\language\Config\LanguageConfigOverride;
 
 /**
- * Defines the plural string textfield elements for the configuration translation interface.
+ * Defines the plural string textfield elements for the configuration
+ * translation interface.
  */
 class PluralString extends FormElementBase {
 
@@ -29,11 +31,11 @@ protected function getSourceElement(LanguageInterface $source_language, $source_
     for ($i = 0; $i < 2; $i++) {
       $element[] = array(
         '#type' => 'item',
-        '#title' => $this->t('!label <span class="visually-hidden">(!source_language)</span>', array(
-          '!label' => ($i == 0 ? 'Singular form' : 'Plural form'),
-          '!source_language' => $source_language->getName(),
+        '#title' => $this->t('@label <span class="visually-hidden">(@source_language)</span>', array(
+          '@label' => ($i == 0 ? 'Singular form' : 'Plural form'),
+          '@source_language' => $source_language->getName(),
         )),
-        '#markup' => '<span lang="' . $source_language->getId() . '">' . nl2br($values[$i]) . '</span>',
+        '#markup' => '<span lang="' . $source_language->getId() . '">' . SafeMarkup::format($values[$i]) . '</span>',
       );
     }
     return $element;
@@ -51,13 +53,13 @@ protected function getTranslationElement(LanguageInterface $translation_language
       '#tree' => TRUE,
     );
     for ($i = 0; $i < $plurals; $i++) {
-      $element[$i] = array(
+      $element[] = array(
         '#type' => 'textfield',
-        '#title' => $this->t('!label <span class="visually-hidden">(!source_language)</span>', array(
-          '!label' => ($i == 0 ? $this->t('Singular form') : $this->formatPlural($i, 'First plural form', '@count. plural form')),
-          '!source_language' => $translation_language->getName(),
+        '#title' => $this->t('@label <span class="visually-hidden">(@source_language)</span>', array(
+          '@label' => ($i == 0 ? $this->t('Singular form') : $this->formatPlural($i, 'First plural form', '@count. plural form')),
+          '@source_language' => $translation_language->getName(),
         )),
-        '#default_value' => $values[$i],
+        '#default_value' => isset($values[$i]) ? $values[$i] : '',
         '#attributes' => array('lang' => $translation_language->getId()),
       );
     }
diff --git a/core/modules/config_translation/src/Tests/ConfigTranslationUiTest.php b/core/modules/config_translation/src/Tests/ConfigTranslationUiTest.php
index dac68fd..252da22 100644
--- a/core/modules/config_translation/src/Tests/ConfigTranslationUiTest.php
+++ b/core/modules/config_translation/src/Tests/ConfigTranslationUiTest.php
@@ -89,6 +89,7 @@ protected function setUp() {
         'administer themes',
         'bypass node access',
         'administer content types',
+        'translate interface',
       ]
     );
     // Create and login user.
@@ -607,32 +608,51 @@ public function testViewsTranslationUI() {
   }
 
   /**
-   * Test translation of plural strings in config.
+   * Test translation of plural strings with multiple plural forms in config.
    */
   public function testPluralConfigStrings() {
     $this->drupalLogin($this->adminUser);
 
+    // First import a .po file with multiple plural forms.
+    // This will also automatically add the 'sl' language.
+    $name = tempnam('temporary://', "sl_") . '.po';
+    file_put_contents($name, $this->getPoFile());
+    $this->drupalPostForm('admin/config/regional/translate/import', array(
+      'langcode' => 'sl',
+      'files[file]' => $name,
+    ), t('Import'));
+    drupal_unlink($name);
+
     // Translate the files view, as this one uses numeric formatters.
     $description = 'Singular form';
     $field_value = '1 place';
     $field_value_plural = '@count places';
-    $translation_url = 'admin/structure/views/view/files/translate/fr/add';
+    $translation_url = 'admin/structure/views/view/files/translate/sl/add';
     $this->drupalGet($translation_url);
 
-    // Make sure original text is present on this page.
+    // Make sure original text is present on this page, in addition to 2 new
+    // empty fields.
     $this->assertRaw($description);
     $this->assertFieldByName('translation[config_names][views.view.files][display][default][display_options][fields][count][format_plural_string][0]', $field_value);
     $this->assertFieldByName('translation[config_names][views.view.files][display][default][display_options][fields][count][format_plural_string][1]', $field_value_plural);
+    $this->assertFieldByName('translation[config_names][views.view.files][display][default][display_options][fields][count][format_plural_string][2]', '');
+    $this->assertFieldByName('translation[config_names][views.view.files][display][default][display_options][fields][count][format_plural_string][3]', '');
+
     // Then make sure it also works.
     $edit = [
-      'translation[config_names][views.view.files][display][default][display_options][fields][count][format_plural_string][0]' => $field_value . ' FR',
-      'translation[config_names][views.view.files][display][default][display_options][fields][count][format_plural_string][1]' => $field_value_plural . ' FR',
+      'translation[config_names][views.view.files][display][default][display_options][fields][count][format_plural_string][0]' => $field_value . ' SL',
+      'translation[config_names][views.view.files][display][default][display_options][fields][count][format_plural_string][1]' => $field_value_plural . ' 1 SL',
+      'translation[config_names][views.view.files][display][default][display_options][fields][count][format_plural_string][2]' => $field_value_plural . ' 2 SL',
+      'translation[config_names][views.view.files][display][default][display_options][fields][count][format_plural_string][3]' => $field_value_plural . ' 3 SL',
     ];
     $this->drupalPostForm($translation_url, $edit, t('Save translation'));
-    // Make sure the values has changed.
+
+    // Make sure the values have changed.
     $this->drupalGet($translation_url);
-    $this->assertFieldByName('translation[config_names][views.view.files][display][default][display_options][fields][count][format_plural_string][0]', "$field_value FR");
-    $this->assertFieldByName('translation[config_names][views.view.files][display][default][display_options][fields][count][format_plural_string][1]', "$field_value_plural FR");
+    $this->assertFieldByName('translation[config_names][views.view.files][display][default][display_options][fields][count][format_plural_string][0]', "$field_value SL");
+    $this->assertFieldByName('translation[config_names][views.view.files][display][default][display_options][fields][count][format_plural_string][1]', "$field_value_plural 1 SL");
+    $this->assertFieldByName('translation[config_names][views.view.files][display][default][display_options][fields][count][format_plural_string][2]', "$field_value_plural 2 SL");
+    $this->assertFieldByName('translation[config_names][views.view.files][display][default][display_options][fields][count][format_plural_string][3]', "$field_value_plural 3 SL");
   }
 
   /**
@@ -962,4 +982,19 @@ protected function assertDisabledTextarea($id) {
     )));
   }
 
+  /**
+   * Helper function that returns a .po file with multiple plural forms.
+   */
+  public function getPoFile() {
+    return <<< EOF
+msgid ""
+msgstr ""
+"Project-Id-Version: Drupal 8\\n"
+"MIME-Version: 1.0\\n"
+"Content-Type: text/plain; charset=UTF-8\\n"
+"Content-Transfer-Encoding: 8bit\\n"
+"Plural-Forms: nplurals=4; plural=(((n%100)==1)?(0):(((n%100)==2)?(1):((((n%100)==3)||((n%100)==4))?(2):3)));\\n"
+EOF;
+  }
+
 }