diff --git a/core/lib/Drupal/Core/StringTranslation/TranslationManager.php b/core/lib/Drupal/Core/StringTranslation/TranslationManager.php
index e9962d6..a8d1eb3 100644
--- a/core/lib/Drupal/Core/StringTranslation/TranslationManager.php
+++ b/core/lib/Drupal/Core/StringTranslation/TranslationManager.php
@@ -134,6 +134,11 @@ public function translateString(TranslatableMarkup $translated_string) {
    *   The translated string.
    */
   protected function doTranslate($string, array $options = array()) {
+    // If a NULL langcode has been provided, unset it.
+    if (array_key_exists('langcode', $options) && $options['langcode'] === NULL) {
+      unset($options['langcode']);
+    }
+
     // Merge in options defaults.
     $options = $options + [
       'langcode' => $this->defaultLangcode,
diff --git a/core/modules/locale/src/Tests/LocalePluralFormatTest.php b/core/modules/locale/src/Tests/LocalePluralFormatTest.php
index ba5cf84..9622bd2 100644
--- a/core/modules/locale/src/Tests/LocalePluralFormatTest.php
+++ b/core/modules/locale/src/Tests/LocalePluralFormatTest.php
@@ -145,6 +145,63 @@ public function testGetPluralFormat() {
   }
 
   /**
+   * Tests plural editing of DateFormatter strings
+   */
+  public function testPluralEditDateFormatter() {
+
+    // Import some .po files with formulas to set up the environment.
+    // These will also add the languages to the system.
+    $this->importPoFile($this->getPoFileWithSimplePlural(), array(
+      'langcode' => 'fr',
+    ));
+
+    // Set French as the site default language.
+    $this->config('system.site')->set('default_langcode', 'fr')->save();
+
+    // Visit User Info page before updating translation strings.
+    $this->drupalGet('user');
+
+    // Member for time should be translated.
+    $this->assertText("seconde", "'Member for' text is translated.");
+
+    $path = 'admin/config/regional/translate/';
+    $search = array(
+      'langcode' => 'fr',
+    );
+    $this->drupalPostForm($path, $search, t('Filter'));
+    // Plural values for the langcode fr.
+    $this->assertText('@count seconde');
+    $this->assertText('@count secondes');
+
+    // Inject a plural source string to the database. We need to use a specific
+    // langcode here because the language will be English by default and will
+    // not save our source string for performance optimization if we do not ask
+    // specifically for a language.
+    \Drupal::translation()->formatPlural(1, '1 second', '@count seconds', array(), array('langcode' => 'fr'))->render();
+    $lid = db_query("SELECT lid FROM {locales_source} WHERE source = :source AND context = ''", array(':source' => "1 second" . LOCALE_PLURAL_DELIMITER . "@count seconds"))->fetchField();
+    // Look up editing page for this plural string and check fields.
+    $search = array(
+      'string' => '1 second',
+      'langcode' => 'fr',
+    );
+    $this->drupalPostForm('admin/config/regional/translate', $search, t('Filter'));
+
+    // Save complete translations for the string in langcode fr.
+    $edit = array(
+      "strings[$lid][translations][0]" => '1 seconde updated',
+      "strings[$lid][translations][1]" => '@count secondes updated',
+    );
+    $this->drupalPostForm($path, $edit, t('Save translations'));
+
+    // User interface input for translating seconds should not be duplicated
+    $this->assertUniqueText('@count seconds', 'Interface translation input for @count seconds only appears once.');
+
+    // Member for time should be translated.
+    $this->drupalGet('user');
+    $this->assertText("seconde", "'Member for' text is translated.");
+  }
+
+  /**
    * Tests plural editing and export functionality.
    */
   public function testPluralEditExport() {
@@ -308,6 +365,11 @@ public function getPoFileWithSimplePlural() {
 msgstr[0] "@count heure"
 msgstr[1] "@count heures"
 
+msgid "1 second"
+msgid_plural "@count seconds"
+msgstr[0] "@count seconde"
+msgstr[1] "@count secondes"
+
 msgid "Monday"
 msgstr "lundi"
 EOF;