diff --git a/src/utils/openmc/summary.py b/src/utils/openmc/summary.py
index ca0905671c..6c7797312e 100644
--- a/src/utils/openmc/summary.py
+++ b/src/utils/openmc/summary.py
@@ -261,7 +261,7 @@ class Summary(object):
             if fill_type == 'normal':
                 fill = self._f['geometry/cells'][key]['material'][0]
             elif fill_type == 'fill':
-                fill = self._f['geometry/cells'][key]['universe'][0]
+                fill = self._f['geometry/cells'][key]['fill'][0]
             else:
                 fill = self._f['geometry/cells'][key]['lattice'][0]
 
@@ -492,4 +492,4 @@ class Summary(object):
             if lattice._id == lattice_id:
                 return lattice
 
-        return None
\ No newline at end of file
+        return None