diff --git a/t/unit-tests/t-reftable-block.c b/t/unit-tests/t-reftable-block.c
index b106d3c1e4..5887e9205d 100644
--- a/t/unit-tests/t-reftable-block.c
+++ b/t/unit-tests/t-reftable-block.c
@@ -83,8 +83,7 @@ static void t_block_read_write(void)
 
 	for (i = 0; i < N; i++) {
 		struct block_iter it = BLOCK_ITER_INIT;
-		strbuf_reset(&want);
-		strbuf_addstr(&want, recs[i].u.ref.refname);
+		reftable_record_key(&recs[i], &want);
 
 		ret = block_iter_seek_key(&it, &br, &want);
 		check_int(ret, ==, 0);