diff -r 6ae6e387a0e3 -r d907601ccad2 includes/comment.php
--- a/includes/comment.php	Wed Feb 06 18:41:47 2008 -0500
+++ b/includes/comment.php	Wed Feb 06 19:27:43 2008 -0500
@@ -262,7 +262,7 @@
         if ( getConfig('comments_need_login') == '1' && !$session->user_logged_in )
         {
           $real_code = $session->get_captcha($data['captcha_id']);
-          if ( $real_code != $data['captcha_code'] )
+          if ( strtolower($real_code) != strtolower($data['captcha_code']) )
             $errors[] = 'The confirmation code you entered was incorrect.';
           $session->kill_captcha();
         }