diff --git a/backref.c b/backref.c
index e1f41e1a..31681a85 100644
--- a/backref.c
+++ b/backref.c
@@ -451,7 +451,7 @@ static int __add_missing_keys(struct btrfs_fs_info *fs_info,
 			continue;
 		BUG_ON(!ref->wanted_disk_byte);
 		eb = read_tree_block(fs_info->tree_root, ref->wanted_disk_byte,
-				     fs_info->tree_root->nodesize, 0);
+				     fs_info->nodesize, 0);
 		if (!extent_buffer_uptodate(eb)) {
 			free_extent_buffer(eb);
 			return -EIO;
@@ -804,7 +804,7 @@ static int find_parent_nodes(struct btrfs_trans_handle *trans,
 			    ref->level == 0) {
 				u32 bsz;
 				struct extent_buffer *eb;
-				bsz = fs_info->extent_root->nodesize;
+				bsz = fs_info->nodesize;
 				eb = read_tree_block(fs_info->extent_root,
 							   ref->parent, bsz, 0);
 				if (!extent_buffer_uptodate(eb)) {
@@ -1154,7 +1154,7 @@ int extent_from_logical(struct btrfs_fs_info *fs_info, u64 logical,
 	}
 	btrfs_item_key_to_cpu(path->nodes[0], found_key, path->slots[0]);
 	if (found_key->type == BTRFS_METADATA_ITEM_KEY)
-		size = fs_info->extent_root->nodesize;
+		size = fs_info->nodesize;
 	else if (found_key->type == BTRFS_EXTENT_ITEM_KEY)
 		size = found_key->offset;