diff --git a/src/backend/access/heap/heapam_handler.c b/src/backend/access/heap/heapam_handler.c
index 6c37d33a0e1..6ecd7631489 100644
--- a/src/backend/access/heap/heapam_handler.c
+++ b/src/backend/access/heap/heapam_handler.c
@@ -1074,9 +1074,14 @@ finalize_block_range(ChangeContext *chgcxt, BlockNumber cur,
 	 * following range (for which we'll use more recent snapshot). Thus it'd
 	 * be non-trivial to apply the UPDATE later. By replaying it now, we get
 	 * rid of the old tuple in the current range.
+	 *
+	 * The scan has passed all blocks before 'cur', not only those before
+	 * 'end': it does not stop at blocks that have no tuples. So 'cur' is the
+	 * upper bound here. The next snapshot is not used for those blocks, so
+	 * changes skipped now would be lost.
 	 */
 	end_of_wal = GetFlushRecPtr(NULL);
-	repack_process_concurrent_changes(chgcxt, end_of_wal, start, end, true,
+	repack_process_concurrent_changes(chgcxt, end_of_wal, start, cur, true,
 									  false);
 
 	/*