in lib/dns/cache.c:dns_cache_renderjson:
	obj = json_object_new_int64(isc_mem_maxinuse(cache->mctx));
	CHECKMEM(obj);
	json_object_object_add(cstats, "HeapMemMax", obj);

should be:
	obj = json_object_new_int64(isc_mem_maxinuse(cache->mctx));
	CHECKMEM(obj);
	json_object_object_add(cstats, "TreeMemMax", obj);

Note that there is a proper HeapMemMax emitted later:
	obj = json_object_new_int64(isc_mem_maxinuse(cache->hmctx));
	CHECKMEM(obj);
	json_object_object_add(cstats, "HeapMemMax", obj);