diff --git a/src/utils/openmc/opencg_compatible.py b/src/utils/openmc/opencg_compatible.py
index 92d8048c3f..90af361488 100644
--- a/src/utils/openmc/opencg_compatible.py
+++ b/src/utils/openmc/opencg_compatible.py
@@ -833,7 +833,8 @@ def get_openmc_geometry(opencg_geometry):
     # Make the entire geometry "compatible" before assigning auto IDs
     universes = opencg_geometry.getAllUniverses()
     for universe_id, universe in universes.items():
-      make_opencg_cells_compatible(universe)
+      if not isinstance(universe, opencg.Lattice):
+        make_opencg_cells_compatible(universe)
 
     opencg_geometry.assignAutoIds()