diff --git a/Catalog/C6_50sqdeg.py b/Catalog/C6_50sqdeg.py
index 00d88888e605422071e5512824f82a3c1ca08bcc..7a0f4dd0849173d1b0decdb1d7f0b61adf2a7d48 100644
--- a/Catalog/C6_50sqdeg.py
+++ b/Catalog/C6_50sqdeg.py
@@ -1,6 +1,7 @@
 import os
 import galsim
 import random
+import copy
 import numpy as np
 import h5py as h5
 import healpy as hp
@@ -290,10 +291,11 @@ class Catalog(CatalogBase):
                 param['agnsed_file'] = ""
                 obj = Galaxy(param, logger=self.logger)
             else:
-                param['star'] = 2   # Quasar
-                param['agnsed_file'] = agnsed_file
+                param_qso = copy.deepcopy(param)
+                param_qso['star'] = 2   # Quasar
+                param_qso['agnsed_file'] = agnsed_file
                 # First add QSO model
-                obj = Quasar(param, logger=self.logger)
+                obj = Quasar(param_qso, logger=self.logger)
                 # Need to deal with additional output columns
                 obj.additional_output_str = self.add_fmt%("n", 0., 0., 0., 0., 0., 0., 0., 0., 0., 0., 0., 0.,
                                                         0, 0.)