--- imagefield_widget.inc	2009-10-09 15:23:27.640625000 +1100
+++ imagefield_widget.inc	2009-10-09 15:24:39.828125000 +1100
@@ -233,6 +233,7 @@ function imagefield_widget_process($elem
     '#description' => t('This text will be used by screen readers, search engines, or when the image cannot be loaded.'),
     '#maxlength' => variable_get('imagefield_alt_length', 80), // See http://www.gawds.org/show.php?contentid=28.
     '#attributes' => array('class' => 'imagefield-text'),
+    '#required' => TRUE,
   );
   // #value must be hard-coded if #type = 'value'.
   if ($default_alt) {