Fix issue #935 [ci skip]
diff --git a/system/language/english/form_validation_lang.php b/system/language/english/form_validation_lang.php
index 0217761..cf1b3b5 100644
--- a/system/language/english/form_validation_lang.php
+++ b/system/language/english/form_validation_lang.php
@@ -43,8 +43,8 @@
$lang['regex_match'] = 'The %s field is not in the correct format.';
$lang['matches'] = 'The %s field does not match the %s field.';
$lang['is_unique'] = 'The %s field must contain a unique value.';
-$lang['is_natural'] = 'The %s field must contain only positive numbers.';
-$lang['is_natural_no_zero'] = 'The %s field must contain a number greater than zero.';
+$lang['is_natural'] = 'The %s field must only contain digits.';
+$lang['is_natural_no_zero'] = 'The %s field must only contain digits and must be greater than zero.';
$lang['decimal'] = 'The %s field must contain a decimal number.';
$lang['less_than'] = 'The %s field must contain a number less than %s.';
$lang['less_than_equal_to'] = 'The %s field must contain a number less than or equal to %s.';