diff --git a/src/View/Geometry/Window.py b/src/View/Geometry/Window.py
index 13f25e30..0f780035 100644
--- a/src/View/Geometry/Window.py
+++ b/src/View/Geometry/Window.py
@@ -20,6 +20,7 @@ import os
 import sys
 import time
 import pathlib
+from pathlib import Path
 import logging
 
 from copy import deepcopy
@@ -685,10 +686,18 @@ class GeometryWindow(PamhyrWindow):
         )
 
         if filename != '' and filename is not None:
-            self._export_to_file_st(filename)
+            suffix = Path(filename).suffix
+            if suffix != "":
+                if suffix == ".st" or suffix == ".ST":
+                    self._export_to_file_st(filename[:-3])
+                else:
+                    # TODO : prévenir l'utilisateur que le format n'est pas exportable
+                    pass
+            else:
+                self._export_to_file_st(filename)
 
     def _export_to_file_st(self, filename):
-        with open(filename, "w+") as f:
+        with open(filename+".st", "w+") as f:
             f.write("# Exported from Pamhyr2\n")
             self._export_to_file_st_reach(f, self._reach)