diff --git a/midx-write.c b/midx-write.c
index a25cab75ab..9328f65a20 100644
--- a/midx-write.c
+++ b/midx-write.c
@@ -1152,7 +1152,7 @@ static bool midx_needs_update(struct multi_pack_index *midx, struct write_midx_c
 
 	/*
 	 * Ensure that we have a valid checksum before consulting the
-	 * exisiting MIDX in order to determine if we can avoid an
+	 * existing MIDX in order to determine if we can avoid an
 	 * update.
 	 *
 	 * This is necessary because the given MIDX is loaded directly
@@ -1208,14 +1208,16 @@ static bool midx_needs_update(struct multi_pack_index *midx, struct write_midx_c
 			BUG("same pack added twice?");
 	}
 
-	for (uint32_t i = 0; i < ctx->nr; i++) {
-		strbuf_reset(&buf);
-		strbuf_addstr(&buf, midx->pack_names[i]);
-		strbuf_strip_suffix(&buf, ".idx");
+	for (struct multi_pack_index *m = midx; m; m = m->base_midx) {
+		for (uint32_t i = 0; i < m->num_packs; i++) {
+			strbuf_reset(&buf);
+			strbuf_addstr(&buf, m->pack_names[i]);
+			strbuf_strip_suffix(&buf, ".idx");
 
-		if (!strset_contains(&packs, buf.buf))
-			goto out;
-		strset_remove(&packs, buf.buf);
+			if (!strset_contains(&packs, buf.buf))
+				goto out;
+			strset_remove(&packs, buf.buf);
+		}
 	}
 
 	needed = false;
diff --git a/t/t5334-incremental-multi-pack-index.sh b/t/t5334-incremental-multi-pack-index.sh
index 99c7d44d8e..c9f5b4e87a 100755
--- a/t/t5334-incremental-multi-pack-index.sh
+++ b/t/t5334-incremental-multi-pack-index.sh
@@ -132,4 +132,20 @@ test_expect_success 'relink existing MIDX layer' '
 
 '
 
+test_expect_success 'non-incremental write with existing incremental chain' '
+	git init non-incremental-write-with-existing &&
+	test_when_finished "rm -fr non-incremental-write-with-existing" &&
+
+	(
+		cd non-incremental-write-with-existing &&
+
+		git config set maintenance.auto false &&
+
+		write_midx_layer &&
+		write_midx_layer &&
+
+		git multi-pack-index write
+	)
+'
+
 test_done