diff --git a/src/backend/access/heap/pruneheap.c b/src/backend/access/heap/pruneheap.c
index a8025889be..7bf73f4d93 100644
--- a/src/backend/access/heap/pruneheap.c
+++ b/src/backend/access/heap/pruneheap.c
@@ -467,6 +467,9 @@ heap_page_prune_and_freeze(Relation relation, Buffer buffer,
 	prstate.visibility_cutoff_xid = InvalidTransactionId;
 
 	maxoff = PageGetMaxOffsetNumber(page);
+
+	/* block and tableOid is the same for all tuples, set it once outside the loop */
+	ItemPointerSetBlockNumber(&tup.t_self, blockno);
 	tup.t_tableOid = RelationGetRelid(relation);
 
 	/*
@@ -540,7 +543,7 @@ heap_page_prune_and_freeze(Relation relation, Buffer buffer,
 		htup = (HeapTupleHeader) PageGetItem(page, itemid);
 		tup.t_data = htup;
 		tup.t_len = ItemIdGetLength(itemid);
-		ItemPointerSet(&tup.t_self, blockno, offnum);
+		ItemPointerSetOffsetNumber(&tup.t_self, offnum);
 
 		prstate.htsv[offnum] = heap_prune_satisfies_vacuum(&prstate, &tup,
 														   buffer);