diff --git a/src/backend/commands/vacuumlazy.c b/src/backend/commands/vacuumlazy.c
index 8dad8c269c..6db6c5cf47 100644
--- a/src/backend/commands/vacuumlazy.c
+++ b/src/backend/commands/vacuumlazy.c
@@ -1754,6 +1754,7 @@ static bool
 heap_page_is_all_visible(Relation rel, Buffer buf, TransactionId *visibility_cutoff_xid)
 {
 	Page		page = BufferGetPage(buf);
+	BlockNumber	blockno = BufferGetBlockNumber(buf);
 	OffsetNumber offnum,
 				maxoff;
 	bool		all_visible = true;
@@ -1778,7 +1779,7 @@ heap_page_is_all_visible(Relation rel, Buffer buf, TransactionId *visibility_cut
 		if (!ItemIdIsUsed(itemid) || ItemIdIsRedirected(itemid))
 			continue;
 
-		ItemPointerSet(&(tuple.t_self), BufferGetBlockNumber(buf), offnum);
+		ItemPointerSet(&(tuple.t_self), blockno, offnum);
 
 		/*
 		 * Dead line pointers can have index pointers pointing to them. So