diff --git a/sandbox/grist/table.py b/sandbox/grist/table.py
index 975da063..ceca65fd 100644
--- a/sandbox/grist/table.py
+++ b/sandbox/grist/table.py
@@ -342,8 +342,9 @@ class Table(object):
     _updateSummary.is_private = True
     col_id = summary_table._summary_helper_col_id
     if self.has_column(col_id):
-      # Column type may have changed, replace completely
-      self.delete_column(self.get_column(col_id))
+      # If type changed between Reference/ReferenceList, replace completely.
+      if type(self.get_column(col_id).type_obj) != type(_updateSummary.grist_type):
+        self.delete_column(self.get_column(col_id))
     col_obj = self._create_or_update_col(col_id, _updateSummary)
     self._special_cols[col_id] = col_obj
     self.all_columns[col_id] = col_obj