diff --git a/CHANGELOG.md b/CHANGELOG.md
index 6335fe23..82832882 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -10,6 +10,7 @@ CHANGELOG for FlatCAM Evo beta
 05.05.2023
 
 - fixed an erroneous opening for a Gerber file generated by KiCAD 6.0.11, due of a rectangular flash being eliminated by the global unary_union operation
+- replaced some type hints with using the Union
 
 15.04.2023
 
diff --git a/appMain.py b/appMain.py
index 16550e3c..026a2c9f 100644
--- a/appMain.py
+++ b/appMain.py
@@ -51,6 +51,8 @@ import qdarktheme
 import qdarktheme.themes.dark.stylesheet as qdarksheet
 import qdarktheme.themes.light.stylesheet as qlightsheet
 
+from typing import Union
+
 # ####################################################################################################################
 # ###################################      Imports part of FlatCAM       #############################################
 # ####################################################################################################################
@@ -6826,7 +6828,7 @@ class App(QtCore.QObject):
         return [self._mouse_click_pos[0], self._mouse_click_pos[1]]
 
     @mouse_click_pos.setter
-    def mouse_click_pos(self, m_pos: list[float] | tuple[float]):
+    def mouse_click_pos(self, m_pos: Union[list[float], tuple[float]]):
         self._mouse_click_pos = m_pos
 
     @property
@@ -6834,7 +6836,7 @@ class App(QtCore.QObject):
         return [self._mouse_pos[0], self._mouse_pos[1]]
 
     @mouse_pos.setter
-    def mouse_pos(self, m_pos: list[float] | tuple[float]):
+    def mouse_pos(self, m_pos: Union[list[float], tuple[float]]):
         self._mouse_pos = m_pos
 
     def selection_area_handler(self, start_pos, end_pos, sel_type):