diff --git a/src/gui_qt/io/asciireader.py b/src/gui_qt/io/asciireader.py
index ea559c2..5fb765b 100644
--- a/src/gui_qt/io/asciireader.py
+++ b/src/gui_qt/io/asciireader.py
@@ -317,10 +317,13 @@ class QAsciiReader(QtWidgets.QDialog, Ui_ascii_reader):
 
         return val
 
-    def check_column_numbers(self, values: int | list[int] | None, num_column: int) -> bool:
+    def check_column_numbers(self, values: int | list[int] | str | None, num_column: int) -> bool:
         is_valid = False
         if values is None:
             is_valid = True
+        elif values == 'index':
+            is_valid = True
+
         elif isinstance(values, int):
             is_valid = values < num_column
         elif isinstance(values, list):