--- trunk/lib/WebPAC/Normalize.pm	2007/11/27 22:31:09	1066
+++ trunk/lib/WebPAC/Normalize.pm	2008/10/26 15:57:37	1118
@@ -47,6 +47,8 @@
 	marc_template
 /);
 
+use Storable qw/dclone/;
+
 =head1 NAME
 
 WebPAC::Normalize - describe normalisaton rules using sets
@@ -364,10 +366,12 @@
 
 	warn "## _pack_subfields_hash( ",dump(@_), " )\n" if ($debug > 1);
 
-	my ($h,$include_subfields) = @_;
+	my ($hash,$include_subfields) = @_;
 
 	# sanity and ease of use
-	return $h if (ref($h) ne 'HASH');
+	return $hash if (ref($hash) ne 'HASH');
+
+	my $h = dclone( $hash );
 
 	if ( defined($h->{subfields}) ) {
 		my $sfs = delete $h->{subfields} || die "no subfields?";