diff --git a/lib/Simba/CA.pm b/lib/Simba/CA.pm
index 635fee8..4c2682b 100644
--- a/lib/Simba/CA.pm
+++ b/lib/Simba/CA.pm
@@ -17,7 +17,7 @@ use Scalar::Util qw(tainted);
 Readonly my $BUFSIZE => 128 * 1024;
 
 sub new {
-    my ($class) = @_;
+    my ($class, $opt) = @_;
 
     my $self = {};
     bless $self, $class;
@@ -26,6 +26,10 @@ sub new {
     $self->{targets} = [
 	{ host => 'localhost', dir => '/var/tmp', },
     ];
+    $self->{unknown_uid} = 65533;
+    $self->{unknown_gid} = 65533;
+    $self->{fh_log}  = exists($opt->{fh_log}) ? $opt->{fh_log} : \*STDERR;
+    $self->{log_level} = 99;
 
     return $self;
 }
@@ -158,8 +162,8 @@ sub present {
     return unless $st;
     if ($st->mtime          == $f->{m} &&
 	$st->size           == $f->{s} &&
-	$st->uid            == name2uid($f->{o}) &&
-	$st->gid            == name2gid($f->{g}) &&
+	$st->uid            == $self->name2uid($f->{o}) &&
+	$st->gid            == $self->name2gid($f->{g}) &&
 	($st->mode & 07777) == $self->acl2mode($f)
     ) {
        	return 1;
@@ -226,7 +230,7 @@ sub setmeta {
     my $mode = $self->acl2mode($f);
     print STDERR "$mode is tainted!" if tainted($mode);
     chmod($mode, $fn);
-    chown(name2uid($f->{o}), name2gid($f->{g}), $fn);
+    chown($self->name2uid($f->{o}), $self->name2gid($f->{g}), $fn);
     utime(time, $f->{m}, $fn);
 }
 
@@ -260,7 +264,7 @@ sub acl2mode {
 
 my %ucache;
 sub name2uid {
-    my ($uname) = @_;
+    my ($self, $uname) = @_;
     $uname = $1 if $uname =~ /(.*)/; # detaint
     return $ucache{$uname} if (defined $ucache{$uname});
     if ($uname =~ /^\d+$/) {
@@ -270,14 +274,14 @@ sub name2uid {
         if (defined($uid)) {
             return $ucache{$uname} = $uid;
         } else {
-            return $ucache{$uname} = -2;
+            return $ucache{$uname} = $self->{unknown_uid};
         }
     }
 }
 
 my %gcache;
 sub name2gid {
-    my ($gname) = @_;
+    my ($self, $gname) = @_;
     $gname = $1 if $gname =~ /(.*)/; # detaint
     return $gcache{$gname} if (defined $gcache{$gname});
     if ($gname =~ /^\d+$/) {
@@ -287,10 +291,23 @@ sub name2gid {
         if (defined($gid)) {
             return $gcache{$gname} = $gid;
         } else {
-            return $gcache{$gname} = -2;
+            return $gcache{$gname} = $self->{unknown_gid};
         }
     }
 }
 
+sub log {
+    my ($self, $level, $msg) = @_;
+    if ($level <= $self->{log_level}) {
+        $self->{fh_log}->print(strftime("%Y-%m-%dT%H:%M:%S%z", localtime), " $$ [$level]: $msg\n");
+    }
+}
+
+sub log_level {
+    my ($self, $log_level) = @_;
+    $self->{log_level}  = $log_level if defined($log_level);
+    return $self->{log_level};
+}
+
 # vim: tw=0 expandtab
 1;
diff --git a/t/01_ca.t b/t/01_ca.t
index 1203672..ae993c5 100644
--- a/t/01_ca.t
+++ b/t/01_ca.t
@@ -2,7 +2,7 @@
 use warnings;
 use strict;
 
-use Test::More 'no_plan';
+use Test::More tests => 15;
 
 BEGIN { use_ok( 'Simba::CA' ); }
 
@@ -10,11 +10,11 @@ my $ca = Simba::CA->new();
 ok($ca, 'new CA');
 
 my $uid;
-$uid = Simba::CA::name2uid('root');
+$uid = $ca->name2uid('root');
 ok(defined($uid), 'root has uid');
 cmp_ok($uid, '==', 0, 'root has correct uid');
 
-$uid = Simba::CA::name2uid('bin');
+$uid = $ca->name2uid('bin');
 ok(defined($uid), 'bin has uid');
 my $bin_uid;
 {
@@ -27,7 +27,7 @@ my $bin_uid;
 }
 cmp_ok($uid, '==', $bin_uid, 'bin has correct uid');
 
-$uid = Simba::CA::name2uid('daemon');
+$uid = $ca->name2uid('daemon');
 ok(defined($uid), 'daemon has uid');
 my $daemon_uid;
 {
@@ -40,15 +40,15 @@ my $daemon_uid;
 }
 cmp_ok($uid, '==', $daemon_uid, 'daemon has correct uid');
 
-$uid = Simba::CA::name2uid('4711');
+$uid = $ca->name2uid('4711');
 ok(defined($uid), 'numerical "user name" has uid');
 cmp_ok($uid, '==', 4711, 'numerical "user name" has correct uid');
 
-$uid = Simba::CA::name2uid('i.am.quite.sure.that.this.is.not.a.real.username');
+$uid = $ca->name2uid('i.am.quite.sure.that.this.is.not.a.real.username');
 ok(defined($uid), 'unknown user has uid');
-cmp_ok($uid, '==', -2, 'unknown user has correct uid');
+cmp_ok($uid, '==', $ca->{unknown_uid}, 'unknown user has correct uid');
 
-my $gid = Simba::CA::name2gid('adm');
+my $gid = $ca->name2gid('adm');
 ok(defined($gid), 'adm has gid');
 my $adm_gid;
 {
@@ -61,3 +61,23 @@ my $adm_gid;
 }
 cmp_ok($gid, '==', $adm_gid, 'adm has correct gid');
 
+SKIP: {
+    skip "not running as root", 1 unless $> == 0;
+    mkdir "t/backup";
+    mkdir "t/backup/1";
+    open my $fh, '>:raw', 't/backup/1/t1';
+    print $fh "test\n";
+    close($fh);
+    chown($ca->{unknown_uid}, $ca->{unknown_gid}, 't/backup/1/t1');
+    chmod(0644, 't/backup/1/t1');
+    my $f = {
+	name => 't1',
+	m    => time(),
+	s    => 5,
+	o    => $ca->{unknown_uid},
+	g    => $ca->{unknown_gid},
+	acl  => 'u::rw-,g::r--,o:r--',
+    };
+    $ca->{last_backup} = 't/backup/1';
+    ok($ca->present($f), "file with unknown owner is present");
+}