diff --git a/src/caosadvancedtools/table_json_conversion/table_generator.py b/src/caosadvancedtools/table_json_conversion/table_generator.py
index 806d1d3c76292a192720fb93991d334ff81c346e..1b52204e77b4b63d06d0fbc4d813c0a10fa2994b 100644
--- a/src/caosadvancedtools/table_json_conversion/table_generator.py
+++ b/src/caosadvancedtools/table_json_conversion/table_generator.py
@@ -28,7 +28,7 @@ import sys
 from abc import ABC, abstractmethod
 from argparse import RawTextHelpFormatter
 from enum import Enum
-from typing import Union
+from typing import Dict, List, Tuple, Union
 
 from openpyxl import Workbook
 from openpyxl.workbook.child import INVALID_TITLE_REGEX
@@ -74,7 +74,7 @@ class TableTemplateGenerator(ABC):
         pass
 
     def _generate_sheets_from_schema(self, schema: dict, foreign_keys: dict = None
-                                     ) -> dict[str, dict[str, list]]:
+                                     ) -> Dict[str, Dict[str, list]]:
         """ generates a sheet definition from a given JSON schema
 
         Parameters
@@ -104,7 +104,7 @@ class TableTemplateGenerator(ABC):
             foreign_keys = {}
         # here, we treat the top level
         # sheets[sheetname][colname]= (COL_TYPE, description, [path])
-        sheets: dict[str, dict[str, tuple[str, list]]] = {}
+        sheets: Dict[str, dict[str, Tuple[str, list]]] = {}
         if "properties" not in schema:
             raise ValueError("Inappropriate JSON schema: The following part should contain "
                              f"the 'properties' key:\n{schema}\n")
@@ -141,7 +141,7 @@ class TableTemplateGenerator(ABC):
     def _treat_schema_element(self, schema: dict, sheets: dict = None, path: list = None,
                               foreign_keys: dict = None, level_in_sheet_name: int = 1,
                               array_paths: list = None
-                              ) -> dict[str, tuple[str, str, list]]:
+                              ) -> Dict[str, Tuple[str, str, list]]:
         """ recursively transforms elements from the schema into column definitions
 
         sheets is modified in place.