diff --git a/system/libraries/Form_validation.php b/system/libraries/Form_validation.php
index 4bb29e4..484e306 100644
--- a/system/libraries/Form_validation.php
+++ b/system/libraries/Form_validation.php
@@ -1277,7 +1277,7 @@
 	 */
 	public function is_natural_no_zero($str)
 	{
-		return ($str !== 0 && preg_match('/^[0-9]+$/', $str));
+		return ($str && preg_match('/^[0-9]+$/', $str));
 	}
 
 	// --------------------------------------------------------------------