diff --git a/admin/marc_subfields_structure.pl b/admin/marc_subfields_structure.pl
index 615fbcfc70..d347012101 100755
--- a/admin/marc_subfields_structure.pl
+++ b/admin/marc_subfields_structure.pl
@@ -425,7 +425,7 @@ elsif ( $op eq 'add_validate' ) {
         my $isurl  = $input->param("isurl$i") ? 1 : 0;
         my $link   = $link[$i];
         my $defaultvalue = $defaultvalue[$i];
-        my $maxlength = $maxlength[$i];
+        my $maxlength = $maxlength[$i] ? $maxlength[$i] : 9999;
         
         if (defined($liblibrarian) && $liblibrarian ne "") {
             unless ( C4::Context->config('demo') eq 1 ) {