bitset_to_array causing memory limit error in 64bit php

Question

I'm trying to append data to a Zend_Search_Lucene index but I'm getting a memory limit error on a line of on line 1584 of Zend_Search_Lucene_Index_SegmentInfo that has this

 $bitCount = count(bitset_to_array($delBytes));

It runs fine on our development servers but when ported to another server that's when I get the error. The difference between the two is that the one that works is a 32bit server and the one where it doesn't work is a 64bit server. I suspect this is the reason and would like to know if anyone else encountered this issue and is there a patch available (I'm trying to avoid having to rework the solution to be 32bit)