diff --git a/modules/field_ui/field_ui.admin.inc b/modules/field_ui/field_ui.admin.inc
index 94fe876c58d3f1df4742551e1226566e9603fe76..5b83838760db3d0b16d9f599d7c266a9c1951588 100644
--- a/modules/field_ui/field_ui.admin.inc
+++ b/modules/field_ui/field_ui.admin.inc
@@ -515,7 +515,7 @@ function _field_ui_field_overview_form_validate_add_new($form, &$form_state) {
       // Add the 'field_' prefix.
       if (substr($field_name, 0, 6) != 'field_') {
         $field_name = 'field_' . $field_name;
-        form_set_value($form['_add_new_field']['field_name'], $field_name, $form_state);
+        form_set_value($form['table']['_add_new_field']['field_name'], $field_name, $form_state);
       }
 
       // Invalid field name.
diff --git a/modules/field_ui/field_ui.test b/modules/field_ui/field_ui.test
index 4a82c7a2ee464bfa4bcb919626cbc7932cf3c64d..5baaa341af44a77452884ab9508da25b3c0547e5 100644
--- a/modules/field_ui/field_ui.test
+++ b/modules/field_ui/field_ui.test
@@ -34,7 +34,8 @@ class FieldUITestCase extends DrupalWebTestCase {
 
     // Create random field name.
     $this->field_label = $this->randomName(8);
-    $this->field_name = 'field_' . strtolower($this->randomName(8));
+    $this->field_name_input =  strtolower($this->randomName(8));
+    $this->field_name = 'field_'. $this->field_name_input;
   }
 
   /**
@@ -85,7 +86,7 @@ class FieldUITestCase extends DrupalWebTestCase {
     // Create a test field.
     $edit = array(
       '_add_new_field[label]' => $this->field_label,
-      '_add_new_field[field_name]' => $this->field_name,
+      '_add_new_field[field_name]' => $this->field_name_input,
     );
     $this->fieldUIAddNewField('admin/structure/types/manage/' . $this->hyphen_type, $edit);