--- captcha.module.old	2007-01-30 12:17:10.000000000 -0800
+++ captcha.module	2007-01-30 14:57:55.000000000 -0800
@@ -114,6 +114,7 @@
 
   if ($_SESSION['captcha_correct']) return TRUE;
   if (is_array($captcha_response)) $captcha_response = $captcha_response['#value'];
+  if (trim($captcha_response) == '') return FALSE;
 
   global $user;
   $captcha_type = variable_get("captcha_type", NULL);