--- taxonomy.module	2006-12-21 17:14:43.000000000 +0000
+++ taxonomy.module.new	2007-01-05 20:38:59.000000000 +0000
@@ -1183,6 +1183,7 @@
     '#multiple' => $multiple,
     '#size' => $multiple ? min(9, count($options)) : 0,
     '#weight' => -15,
+    '#required' => !$blank,
     '#theme' => 'taxonomy_term_select',
   );
 }