diff -up bind-9.3.6-P1/lib/dns/db.c.db_unregister bind-9.3.6-P1/lib/dns/db.c --- bind-9.3.6-P1/lib/dns/db.c.db_unregister 2004-03-08 03:07:52.000000000 +0100 +++ bind-9.3.6-P1/lib/dns/db.c 2009-04-24 12:58:19.335265774 +0200 @@ -790,4 +790,6 @@ dns_db_unregister(dns_dbimplementation_t isc_mem_put(mctx, imp, sizeof(dns_dbimplementation_t)); isc_mem_detach(&mctx); RWUNLOCK(&implock, isc_rwlocktype_write); + + *dbimp = NULL; }