diff --git a/openmc/mgxs/mgxs.py b/openmc/mgxs/mgxs.py
index 172d7ddb38..b077d04d1d 100644
--- a/openmc/mgxs/mgxs.py
+++ b/openmc/mgxs/mgxs.py
@@ -2774,7 +2774,7 @@ class TransportXS(MGXS):
             p1_tally = p1_tally.get_slice(filters=[openmc.LegendreFilter],
                                           filter_bins=[('P1',)],
                                           squeeze=True)
-            p1_tally.scores = ['scatter-1']
+            p1_tally._scores = ['scatter-1']
 
             # Compute total cross section
             total_xs = self.tallies['total'] / self.tallies['flux (tracklength)']