diff --git a/sio2/sisr/20-python/exo4.py b/sio2/sisr/20-python/exo4.py
index 0b7bc06..3ee15f3 100644
--- a/sio2/sisr/20-python/exo4.py
+++ b/sio2/sisr/20-python/exo4.py
@@ -29,6 +29,6 @@ def main(filename):
 
 if __name__ == "__main__":
     if len(sys.argv) != 2:
-        print("Usage: python creatusr.py <nom_du_fichier>")
+        print("Usage: python exo4.py <nom_du_fichier>")
     else:
         main(sys.argv[1])