diff --git a/Control/CalypsoExample/Generation/python/faser_parser.py b/Control/CalypsoExample/Generation/python/faser_parser.py
index ff50f4cf9d9667e4c75bad1d76a91c8964ea110b..c98d348aea5ccc2e2b3c1459ef793bd41bb8c3e9 100644
--- a/Control/CalypsoExample/Generation/python/faser_parser.py
+++ b/Control/CalypsoExample/Generation/python/faser_parser.py
@@ -47,7 +47,7 @@ def faser_pgparser():
     parser.add_argument("--zpos", default=None, type=float,
                         help="Specify z position of particles (in mm) (helpful to avoid FASERnu)")
 
-    parser.add_argument("--pidd1", default=211, type=int, 
+    parser.add_argument("--pidd1", default=None, type=int, 
                         help="Specify PDG ID of daugther 1 for DIF generator")
     parser.add_argument("--pidd2", default=None, type=int, 
                         help="Specify PDG ID of daugther 2 for DIF generator")