diff --git a/core/lib/Drupal/Core/Field/Plugin/Field/FieldFormatter/NumericFormatterBase.php b/core/lib/Drupal/Core/Field/Plugin/Field/FieldFormatter/NumericFormatterBase.php
index b0f5eec..7d36998 100644
--- a/core/lib/Drupal/Core/Field/Plugin/Field/FieldFormatter/NumericFormatterBase.php
+++ b/core/lib/Drupal/Core/Field/Plugin/Field/FieldFormatter/NumericFormatterBase.php
@@ -77,15 +77,16 @@ public function settingsForm(array $form, FormStateInterface $form_state) {
       ),
     );
 
-    // @todo This field needs to have some kind of #states magic so that it
-    // only shows if the option on format_plural is
-    // NumericFormatterBase::FORMAT_PLURAL_USE_FORMATTER_SETTING.
-    // Need to do this before this patch is finalized!
-    $elements['format_plural_values'] = array(
+    $elements['format_plural_values'] = [
       '#type' => 'fieldset',
       '#title' => $this->t('Prefix/suffix override'),
       '#after_build' => [[get_class($this), 'formatPluralValuesAfterBuild']],
-    );
+      '#states' => [
+        'visible' => [
+          ':input[name*="format_plural"]' => ['value' => NumericFormatterBase::FORMAT_PLURAL_USE_FORMATTER_SETTING],
+        ],
+      ],
+    ];
 
     $langcode = $this->getSetting('_settings_langcode');
     $plurals = $this->getNumberOfPlurals($langcode);