diff --git a/src/backend/utils/mb/Unicode/convutils.pm b/src/backend/utils/mb/Unicode/convutils.pm
index 69ec099..e57342c 100644
--- a/src/backend/utils/mb/Unicode/convutils.pm
+++ b/src/backend/utils/mb/Unicode/convutils.pm
@@ -254,6 +254,9 @@ sub print_radix_table
 	my %b4map;
 	foreach my $in (keys %$c)
 	{
+		# silence perl diagnostic about portability of 0x100000000
+		no warnings qw(portable);
+
 		my $out = $c->{$in};
 
 		if ($in < 0x100)