diff --git a/lib/Qpsmtpd.pm b/lib/Qpsmtpd.pm
index 79a3623..be1cea4 100644
--- a/lib/Qpsmtpd.pm
+++ b/lib/Qpsmtpd.pm
@@ -591,7 +591,7 @@ sub spool_dir {
     unless ($Spool_dir) {    # first time through
         $self->log(LOGDEBUG, "Initializing spool_dir");
         $Spool_dir = $self->config('spool_dir')
-          || Qpsmtpd::Utils::tildeexp('~/tmp/');
+          || Qpsmtpd::Utils->tildeexp('~/tmp/');
 
         $Spool_dir .= "/" unless ($Spool_dir =~ m!/$!);
 
diff --git a/lib/Qpsmtpd/Utils.pm b/lib/Qpsmtpd/Utils.pm
index 38c2c6f..edd8d4e 100644
--- a/lib/Qpsmtpd/Utils.pm
+++ b/lib/Qpsmtpd/Utils.pm
@@ -2,13 +2,22 @@ package Qpsmtpd::Utils;
 use strict;
 
 sub tildeexp {
-    my $path = shift;
+    my ($self, $path) = @_;
     $path =~ s{^~([^/]*)} {  
-	  $1 
+	  $1
 	      ? (getpwnam($1))[7] 
 	      : ( $ENV{HOME} || $ENV{LOGDIR} || (getpwuid($>))[7])
 	  }ex;
     return $path;
 }
 
+sub is_localhost {
+    my ($self, $ip) = @_;
+    return if ! $ip;
+    return 1 if $ip =~ /^127\./;  # IPv4
+    return 1 if $ip =~ /:127\./;  # IPv4 mapped IPv6
+    return 1 if $ip eq '::1';     # IPv6
+    return;
+}
+
 1;
diff --git a/plugins/helo b/plugins/helo
index b068672..d4e3a8c 100644
--- a/plugins/helo
+++ b/plugins/helo
@@ -340,13 +340,14 @@ sub is_regex_match {
 sub invalid_localhost {
     my ($self, $host) = @_;
     return if lc $host ne 'localhost';
-    if ($self->qp->connection->remote_ip ne '127.0.0.1') {
-
-        #$self->log( LOGINFO, "fail, not localhost" );
-        return ("You are not localhost", "invalid localhost");
+    my $ip = $self->qp->connection->remote_ip;
+    if ($ip && ($ip eq '127.0.0.1' || $ip eq '::1')) {
+        $self->log(LOGDEBUG, "pass, is localhost");
+        return;
     }
-    $self->log(LOGDEBUG, "pass, is localhost");
-    return;
+
+    #$self->log( LOGINFO, "fail, not localhost" );
+    return ("You are not localhost", "invalid localhost");
 }
 
 sub is_plain_ip {
diff --git a/t/plugin_tests/helo b/t/plugin_tests/helo
index 25ba153..8790894 100644
--- a/t/plugin_tests/helo
+++ b/t/plugin_tests/helo
@@ -11,7 +11,7 @@ sub register_tests {
     $self->register_test('test_init_resolver', 2);
     $self->register_test('test_is_in_badhelo', 2);
     $self->register_test('test_is_regex_match', 3);
-    $self->register_test('test_invalid_localhost', 4);
+    $self->register_test('test_invalid_localhost', 5);
     $self->register_test('test_is_plain_ip', 3);
     $self->register_test('test_is_address_literal', 3);
     $self->register_test('test_no_forward_dns', 2);
@@ -73,9 +73,11 @@ sub test_invalid_localhost {
     ($err, $why) = $self->invalid_localhost('localhost');
     ok( $err, "localhost, invalid remote IP: $why");
 
-    $self->qp->connection->remote_ip('127.0.0.1');
-    ($err, $why) = $self->invalid_localhost('localhost');
-    ok( ! $err, "localhost, correct remote IP");
+    foreach my $ip (qw/ ::1 127.0.0.1 / ) {
+        $self->qp->connection->remote_ip($ip);
+        ($err, $why) = $self->invalid_localhost('localhost');
+        ok( ! $err, "localhost, correct remote IP ($ip)");
+    }
 };
 
 sub test_is_plain_ip {
diff --git a/t/qpsmtpd-utils.t b/t/qpsmtpd-utils.t
new file mode 100644
index 0000000..0d278b9
--- /dev/null
+++ b/t/qpsmtpd-utils.t
@@ -0,0 +1,35 @@
+#!/usr/bin/perl
+use strict;
+use warnings;
+
+use Test::More;
+
+use lib 'lib';      # test lib/Qpsmtpd/Utils (vs site_perl)
+
+BEGIN { use_ok('Qpsmtpd::Utils'); }
+
+my $utils = bless {}, 'Qpsmtpd::Utils';
+
+__tildeexp();
+__is_localhost();
+
+done_testing();
+
+sub __is_localhost {
+
+    for my $local_ip (qw/ 127.0.0.1 ::1 2607:f060:b008:feed::127.0.0.1 127.0.0.2 /) {
+        ok( $utils->is_localhost($local_ip), "is_localhost, $local_ip");
+    }
+
+    for my $rem_ip (qw/ 128.0.0.1 ::2 2607:f060:b008:feed::128.0.0.1 /) {
+        ok( !$utils->is_localhost($rem_ip), "!is_localhost, $rem_ip");
+    }
+};
+
+sub __tildeexp {
+    my $path = $utils->tildeexp('~root/foo.txt');
+    ok( $path, "tildeexp, $path");
+
+    $path = $utils->tildeexp('no/tilde/in/path');
+    cmp_ok( $path, 'eq', 'no/tilde/in/path', 'tildeexp, no expansion');
+};