diff --git a/openmc/arithmetic.py b/openmc/arithmetic.py
index 65e12c5d2..8574c4873 100644
--- a/openmc/arithmetic.py
+++ b/openmc/arithmetic.py
@@ -823,7 +823,8 @@ class AggregateFilter(object):
 
         """
 
-        if filter_bin not in self.bins:
+        if filter_bin not in self.bins and \
+           filter_bin != self._aggregate_filter.bins:
             msg = 'Unable to get the bin index for AggregateFilter since ' \
                   '"{0}" is not one of the bins'.format(filter_bin)
             raise ValueError(msg)
diff --git a/openmc/mgxs/library.py b/openmc/mgxs/library.py
index 4b8d8a914..e87b4bdae 100644
--- a/openmc/mgxs/library.py
+++ b/openmc/mgxs/library.py
@@ -568,8 +568,9 @@ class Library(object):
         for domain in self.domains:
             for mgxs_type in self.mgxs_types:
                 mgxs = subdomain_avg_library.get_mgxs(domain, mgxs_type)
-                avg_mgxs = mgxs.get_subdomain_avg_xs()
-                subdomain_avg_library.all_mgxs[domain.id][mgxs_type] = avg_mgxs
+                if mgxs.domain_type == 'distribcell':
+                    avg_mgxs = mgxs.get_subdomain_avg_xs()
+                    subdomain_avg_library.all_mgxs[domain.id][mgxs_type] = avg_mgxs
 
         return subdomain_avg_library