diff --git a/src/hdmf/data_utils.py b/src/hdmf/data_utils.py
index 53389d7c9..3781abe8e 100644
--- a/src/hdmf/data_utils.py
+++ b/src/hdmf/data_utils.py
@@ -16,7 +16,7 @@ def append_data(data, arg):
     if isinstance(data, (list, DataIO)):
         data.append(arg)
         return data
-    elif type(data).__name__ == 'TermSetWrapper': # circular import 
+    elif type(data).__name__ == 'TermSetWrapper': # circular import
         data.append(arg)
         return data
     elif isinstance(data, np.ndarray):