diff --git a/kernel-shared/free-space-tree.c b/kernel-shared/free-space-tree.c
index 0fdf5004..896bd3a2 100644
--- a/kernel-shared/free-space-tree.c
+++ b/kernel-shared/free-space-tree.c
@@ -1057,6 +1057,9 @@ int populate_free_space_tree(struct btrfs_trans_handle *trans,
 	if (ret)
 		goto out;
 
+	start = block_group->start;
+	end = block_group->start + block_group->length;
+
 	/*
 	 * Iterate through all of the extent and metadata items in this block
 	 * group, adding the free space between them and the free space at the
@@ -1071,10 +1074,11 @@ int populate_free_space_tree(struct btrfs_trans_handle *trans,
 	ret = btrfs_search_slot_for_read(extent_root, &key, path, 1, 0);
 	if (ret < 0)
 		goto out;
-	ASSERT(ret == 0);
+	if (ret > 0) {
+		ASSERT(btrfs_fs_incompat(trans->fs_info, EXTENT_TREE_V2));
+		goto done;
+	}
 
-	start = block_group->start;
-	end = block_group->start + block_group->length;
 	while (1) {
 		btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
 
@@ -1106,6 +1110,7 @@ int populate_free_space_tree(struct btrfs_trans_handle *trans,
 		if (ret)
 			break;
 	}
+done:
 	if (start < end) {
 		ret = __add_to_free_space_tree(trans, block_group, path2,
 				start, end - start);