diff --git a/modules/Bio/EnsEMBL/Pipeline/Production/PercentRepeat.pm b/modules/Bio/EnsEMBL/Pipeline/Production/PercentRepeat.pm
index 66c4be0db7e33c835b4be06eaf0183fa0c4f7bca..d3a260ad218ef2843405bead55df9c3caaffae87 100644
--- a/modules/Bio/EnsEMBL/Pipeline/Production/PercentRepeat.pm
+++ b/modules/Bio/EnsEMBL/Pipeline/Production/PercentRepeat.pm
@@ -11,6 +11,7 @@ use warnings;
 
 sub get_density {
   my ($self, $block) = @_;
+  if ($block->length > 5000000) { return 0; }
   my $repeat_count = 0;
   my @repeats = @{ $block->get_all_RepeatFeatures() };
   @repeats = map { $_->[1] } sort { $a->[0] <=> $b->[0] } map { [$_->start, $_] } @repeats;