diff --git a/core/modules/field/modules/text/text.module b/core/modules/field/modules/text/text.module
index f362fb7..43f821e 100644
--- a/core/modules/field/modules/text/text.module
+++ b/core/modules/field/modules/text/text.module
@@ -229,6 +229,7 @@ function text_field_formatter_settings_form($field, $instance, $view_mode, $form
       '#title' => t('Trim length'),
       '#type' => 'number',
       '#default_value' => $settings['trim_length'],
+      '#element_validate' => array('element_validate_integer_positive'),
       '#min' => 1,
       '#required' => TRUE,
     );