diff --git a/source/fs/mufs/tree.c b/source/fs/mufs/tree.c
index 8585e95..61e3efc 100644
--- a/source/fs/mufs/tree.c
+++ b/source/fs/mufs/tree.c
@@ -35,6 +35,10 @@ static int mufs_do_lookup(struct mufs *fs, uint32_t *page,
 	if (!table[index]) {
 		if (!alloc || mufs_alloc_block(fs, &table[index]) < 0)
 			return -1;
+
+		if (flash_write(fs->dev, base << fs->dev->log2_block_size, data,
+			sizeof data) == 0)
+			return -1;
 	}
 
 	return mufs_do_lookup(fs, page, table[index], depth - 1, va, alloc);