Bug in autovacuum.c?

Looking over the autovacuum.c code, I see:
   /*    * Determine the oldest datfrozenxid/relfrozenxid that we will allow to    * pass without forcing a vacuum.
(Thislimit can be tightened for    * particular tables, but not loosened.)    */   recentXid = ReadNewTransactionId();
xidForceLimit = recentXid - autovacuum_freeze_max_age;   /* ensure it's a "normal" XID, else TransactionIdPrecedes
misbehaves*/   if (xidForceLimit < FirstNormalTransactionId)       xidForceLimit -= FirstNormalTransactionId;
 

This last line doesn't look right to me;  should it be:
       xidForceLimit = FirstNormalTransactionId;

--  Bruce Momjian  <bruce@momjian.us>        http://momjian.us EnterpriseDB
http://enterprisedb.com
 + It's impossible for everything to be true. +