diff --git a/zmldapsync/zmldapsync.pl b/zmldapsync/zmldapsync.pl
index 9df69ff..6252b80 100644
--- a/zmldapsync/zmldapsync.pl
+++ b/zmldapsync/zmldapsync.pl
@@ -375,8 +375,9 @@ DOMAIN: foreach my $domain ( keys $conf->{domains} ) {
     foreach my $mail_attr ( qw( mail_attr alias_attr ) ) {
       next if ( not defined $conf->{domains}->{$domain}->{users}->{$mail_attr} or
                 not defined $ext_users->{$user}->{$conf->{domains}->{$domain}->{users}->{$mail_attr}} );
-      push @ext_aliases,
-             @{ $ext_users->{$user}->{$conf->{domains}->{$domain}->{users}->{$mail_attr}} };
+      push @ext_aliases, ref $ext_users->{$user}->{$conf->{domains}->{$domain}->{users}->{$mail_attr}} eq 'ARRAY' ?
+             @{ $ext_users->{$user}->{$conf->{domains}->{$domain}->{users}->{$mail_attr}} } :
+	     $ext_users->{$user}->{$conf->{domains}->{$domain}->{users}->{$mail_attr}};
     }
 
     @ext_aliases = uniq( sort @ext_aliases );
@@ -622,8 +623,9 @@ DOMAIN: foreach my $domain ( keys $conf->{domains} ) {
       foreach my $mail_attr ( qw( mail_attr alias_attr ) ) {
         next if ( not defined $conf->{domains}->{$domain}->{groups}->{$mail_attr} or
                   not defined $ext_groups->{$group}->{$conf->{domains}->{$domain}->{groups}->{$mail_attr}} );
-        push @ext_aliases,
-               @{ $ext_groups->{$group}->{$conf->{domains}->{$domain}->{groups}->{$mail_attr}} };
+        push @ext_aliases, ref $ext_groups->{$group}->{$conf->{domains}->{$domain}->{groups}->{$mail_attr}} eq 'ARRAY' ?
+             @{ $ext_groups->{$group}->{$conf->{domains}->{$domain}->{groups}->{$mail_attr}} } :
+	     $ext_groups->{$group}->{$conf->{domains}->{$domain}->{groups}->{$mail_attr}};
       }
       @ext_aliases = uniq( sort @ext_aliases );
       foreach my $alias ( @ext_aliases ) {