diff --git a/openmc/mgxs/library.py b/openmc/mgxs/library.py
index 8d5e9854ee..c3529fc98d 100644
--- a/openmc/mgxs/library.py
+++ b/openmc/mgxs/library.py
@@ -575,7 +575,8 @@ class Library(object):
         return subdomain_avg_library
 
     def build_hdf5_store(self, filename='mgxs.h5', directory='mgxs',
-                         subdomains='all', nuclides='all', xs_type='macro'):
+                         subdomains='all', nuclides='all', xs_type='macro',
+                         row_column='inout'):
         """Export the multi-group cross section library to an HDF5 binary file.
 
         This method constructs an HDF5 file which stores the library's
@@ -605,6 +606,10 @@ class Library(object):
         xs_type: {'macro', 'micro'}
             Store the macro or micro cross section in units of cm^-1 or barns.
             Defaults to 'macro'.
+        row_column: {'inout', 'outin'}
+            Store scattering matrices indexed first by incoming group and
+            second by outgoing group ('inout'), or vice versa ('outin').
+            Defaults to 'inout'.
 
         Raises
         ------
@@ -646,8 +651,8 @@ class Library(object):
                 if subdomains == 'avg':
                     mgxs = mgxs.get_subdomain_avg_xs()
 
-                mgxs.build_hdf5_store(filename, directory,
-                                      xs_type=xs_type, nuclides=nuclides)
+                mgxs.build_hdf5_store(filename, directory, xs_type=xs_type,
+                                      nuclides=nuclides, row_column=row_column)
 
     def dump_to_file(self, filename='mgxs', directory='mgxs'):
         """Store this Library object in a pickle binary file.
diff --git a/openmc/mgxs/mgxs.py b/openmc/mgxs/mgxs.py
index 90b956b219..57f42c1eee 100644
--- a/openmc/mgxs/mgxs.py
+++ b/openmc/mgxs/mgxs.py
@@ -1174,8 +1174,9 @@ class MGXS(object):
             Store the macro or micro cross section in units of cm^-1 or barns.
             Defaults to 'macro'.
         row_column: {'inout', 'outin'}
-            Store scattering matrices indexed first by incoming group and second
-            by outgoing group ('inout'), or vice versa ('outin').
+            Store scattering matrices indexed first by incoming group and
+            second by outgoing group ('inout'), or vice versa ('outin').
+            Defaults to 'inout'.
         append : bool
             If true, appends to an existing HDF5 file with the same filename
             directory (if one exists). Defaults to True.
@@ -2005,8 +2006,9 @@ class ScatterMatrixXS(MGXS):
             decreasing energy groups (decreasing or increasing energies).
             Defaults to 'increasing'.
         row_column: {'inout', 'outin'}
-            Return the cross section indexed first by incoming group and second
-            by outgoing group ('inout'), or vice versa ('outin').
+            Return the cross section indexed first by incoming group and
+            second by outgoing group ('inout'), or vice versa ('outin').
+            Defaults to 'inout'.
         value : str
             A string for the type of value to return - 'mean', 'std_dev', or
             'rel_err' are accepted. Defaults to the empty string.