diff --git a/source/fs/mufs/tree.c b/source/fs/mufs/tree.c
index f100b05..6f1e426 100644
--- a/source/fs/mufs/tree.c
+++ b/source/fs/mufs/tree.c
@@ -177,7 +177,8 @@ static size_t mufs_do_read(struct mufs *fs, struct mufs_tree *tree,
 	if (mufs_lookup_page(fs, tree, &page, va) < 0)
 		return 0;
 
-	return flash_read(fs->dev, page, data, len);
+	return flash_read(fs->dev, (page << fs->dev->log2_block_size) + offset,
+		data, len);
 }
 
 size_t mufs_read(struct mufs *fs, struct mufs_tree *tree, void *data,
@@ -209,10 +210,14 @@ static size_t mufs_do_write(struct mufs *fs, struct mufs_tree *tree,
 	memset(data, 0, len);
 	len = min(len, (UINT32_C(1) << fs->dev->log2_block_size) - offset);
 
+	if (mufs_extend_tree(fs, tree, 1) < 0)
+		return 0;
+
 	if (mufs_alloc_page(fs, tree, &page, va) < 0)
 		return 0;
 
-	return flash_write(fs->dev, page, data, len);
+	return flash_write(fs->dev, (page << fs->dev->log2_block_size) + offset,
+		data, len);
 }
 
 size_t mufs_write(struct mufs *fs, struct mufs_tree *tree, void *data,