diff --git a/xscen/catalog.py b/xscen/catalog.py
index b095afe6..377f0279 100644
--- a/xscen/catalog.py
+++ b/xscen/catalog.py
@@ -261,7 +261,7 @@ def unique(self, columns: Union[str, Sequence[str]] = None):
 
         Parameters
         ----------
-        columns : str or list of str, optional
+        columns : str or sequence of str, optional
           The columns to get unique values from. If None, all columns are used.
         """
         if self.df.size == 0: