diff --git a/openmc/filter.py b/openmc/filter.py
index a0c777fa07..54814a6b6f 100644
--- a/openmc/filter.py
+++ b/openmc/filter.py
@@ -673,9 +673,11 @@ class Filter(object):
 
                         # Assign entry to Lattice Multi-index column
                         else:
+                            # Reverse y index per lattice ordering in OpenCG
                             level_dict[lat_id_key][offset] = coords._lattice._id
                             level_dict[lat_x_key][offset] = coords._lat_x
-                            level_dict[lat_y_key][offset] = coords._lat_y
+                            level_dict[lat_y_key][offset] = \
+                                coords._lattice.dimension[1] - coords._lat_y - 1
                             level_dict[lat_z_key][offset] = coords._lat_z
 
                         # Move to next node in LocalCoords linked list
diff --git a/openmc/opencg_compatible.py b/openmc/opencg_compatible.py
index a5573d9eb4..0bda48c160 100644
--- a/openmc/opencg_compatible.py
+++ b/openmc/opencg_compatible.py
@@ -922,9 +922,6 @@ def get_opencg_lattice(openmc_lattice):
                 universe_id = universes[z][y][x].id
                 universe_array[z][y][x] = unique_universes[universe_id]
 
-    # Reverse y-dimension in array to match ordering in OpenCG
-    universe_array = universe_array[:, ::-1, :]
-
     opencg_lattice = opencg.Lattice(lattice_id, name)
     opencg_lattice.dimension = dimension
     opencg_lattice.width = pitch