diff -rupN computed_field.module computed_field.module
--- computed_field.module	2009-01-08 12:08:19.000000000 +0100
+++ computed_field.module	2009-01-08 12:14:26.000000000 +0100
@@ -297,7 +297,10 @@ function theme_computed_field_formatter_
  * Implementation of cck hook_content_is_empty().
  */
 function computed_field_content_is_empty() {
-  return FALSE;
+  if ($field['data_type'] == 'int' || $field['data_type'] == 'float') {
+    return !is_numeric($item['value']);
+  }
+  return empty($item['value']);
 }
 
 /**