diff --git a/source/fs/mufs/tree.c b/source/fs/mufs/tree.c
index 2022d09..aeead8e 100644
--- a/source/fs/mufs/tree.c
+++ b/source/fs/mufs/tree.c
@@ -190,7 +190,8 @@ int mufs_shrink_tree(struct mufs_tree *tree, uint32_t max_size)
 			dev->log2_block_size);
 
 		if (index <= 1) {
-			if (flash_read(dev, base, &tree->root, sizeof tree->root) == 0)
+			if (flash_read(dev, (base << dev->log2_block_size), &tree->root,
+				sizeof tree->root) == 0)
 				return -1;
 
 			--tree->depth;
@@ -200,8 +201,9 @@ int mufs_shrink_tree(struct mufs_tree *tree, uint32_t max_size)
 			continue;
 		}
 
-		if (flash_write0(dev, base + index * sizeof(uint32_t), (UINT32_C(1) <<
-			dev->log2_block_size) - index * sizeof(uint32_t)) == 0)
+		if (flash_write0(dev, (base << dev->log2_block_size) +
+			index * sizeof(uint32_t), (UINT32_C(1) << dev->log2_block_size) -
+			index * sizeof(uint32_t)) == 0)
 			return -1;
 
 		if (flash_sync(dev) < 0)