diff --git a/fluents/selections.py b/fluents/selections.py
index 6629147..8f0470e 100644
--- a/fluents/selections.py
+++ b/fluents/selections.py
@@ -239,6 +239,11 @@ class SelectionListController:
                 n = len(selection[dim])
                 values = (selection.title, selection, dim, n, n, 0)
                 store.insert_after(None, None, values)
+            else:
+                # update size of current selection
+                for row in store:
+                    if row[1]==selection:
+                        row[3] = row[4] = len(selection[dim])
 
     def add_dataset(self, dataset):
         dim_name = dataset.get_dim_name(0)