diff --git a/openmc/mgxs_library.py b/openmc/mgxs_library.py
index fc8467b151..ac12847aaa 100644
--- a/openmc/mgxs_library.py
+++ b/openmc/mgxs_library.py
@@ -137,7 +137,7 @@ class XSdata(object):
     [Order][G][G']: scatter_matrix
 
     [G]: total, absorption, fission, kappa_fission, nu_fission,
-         prompt_nu_fission, inverse_velocity
+         prompt_nu_fission, delayed_nu_fission, inverse_velocity
 
     [G']: chi, chi_prompt, chi_delayed