diff --git a/plugins/parse_addr_withhelo b/plugins/parse_addr_withhelo
index 49c8a0f..2d70e7b 100644
--- a/plugins/parse_addr_withhelo
+++ b/plugins/parse_addr_withhelo
@@ -17,6 +17,11 @@ parameters is done.
 
 =cut
 
+use strict;
+use warnings;
+
+use Qpsmtpd::Constants;
+
 sub hook_mail_parse {
     my $self = shift;
     return (OK, \&_parse) if ($self->qp->connection->hello eq 'helo');