diff --git a/fsl/utils/filetree/__init__.py b/fsl/utils/filetree/__init__.py
index a3cd056f6743f609d502b65863ebe4e3bda15175..d1e2f7f37b455d24bf0fe13729d6b343c41f8ffa 100644
--- a/fsl/utils/filetree/__init__.py
+++ b/fsl/utils/filetree/__init__.py
@@ -309,7 +309,7 @@ You can update the FileTree with one or more variables before calling `get_all_t
 
 .. code-block:: python
 
-    for t in tree.update(participant=('001', '002'), run=("1")).get_all_trees("feat_dir"):
+    for t in tree.update(participant=("001", "002"), run=("1")).get_all_trees("feat_dir"):
         my_pipeline(t)
 
 """