diff --git a/core/modules/field_ui/src/Tests/NumericFieldsUiTest.php b/core/modules/field_ui/src/Tests/NumericFieldsUiTest.php
index ab83778..e647b0e 100644
--- a/core/modules/field_ui/src/Tests/NumericFieldsUiTest.php
+++ b/core/modules/field_ui/src/Tests/NumericFieldsUiTest.php
@@ -99,7 +99,7 @@ public function testNumericFieldUI() {
       $formatter_settings_prefix . '[format_plural_values][0]' => 'OverrideSingularP@countOverrideSingularS',
       $formatter_settings_prefix . '[format_plural_values][1]' => 'OverridePluralP@countOverridePluralS',
     );
-    $this->drupalPostAjaxForm(NULL, $edit, array('op' => t('Refresh')));
+    $this->drupalPostAjaxForm(NULL, $edit, 'field_' . $this->fieldName . '_plugin_settings_update');
     $this->drupalPostForm(NULL, array(), t('Save'));
 
     // Create another node, this time with a plural value, and verify the