Getting ERROR: explicit multiset too large

Hello, I am getting this error when trying to insert HLL's into the DB which seems to break this constraint:
https://github.com/citusdata/postgresql-hll/blob/master/src/hll.c#L554
I am trying to insert millions of id's into the HLL with value for log2m=20 and regWidth=7. This does not cause a problem in java-hll library, but when inserting the HLL into the DB it fails.

The value for **MS_MAXDATA** seems to be too low for practical purposes. I was wondering what the rationale behind this limit is.