diff --git a/bin/slubsipbuilder.pl b/bin/slubsipbuilder.pl
index 86f492ae9a04bf79c37ebdfe77797bc4d16924df..786af1ae8573570bed6c3ea3f9b7beaa743c2cc7 100755
--- a/bin/slubsipbuilder.pl
+++ b/bin/slubsipbuilder.pl
@@ -286,7 +286,7 @@ sub main {
         mkpath("$output") || confess("could not create SIP directory for '$output', $!");
     }
     $output = abs_path($output);
-    my $sip_root_dir = "PPN-${ppn}_${file_date}";
+    my $sip_root_dir = (defined $ppn)? "PPN-${ppn}_${file_date}" : "ID-${noppn}_${file_date}";
     my $content = "$output/$sip_root_dir/data";
     if (!defined $as_zip) {
         mkpath("$output/$sip_root_dir") || confess("could not create SIP directory for '$output/$sip_root_dir', $!");