diff --git a/include/openmc/settings.h b/include/openmc/settings.h
index e873e3d3e2..69231321d4 100644
--- a/include/openmc/settings.h
+++ b/include/openmc/settings.h
@@ -29,7 +29,7 @@ namespace settings {
 
 #ifdef LIBMESH
 extern std::unique_ptr<libMesh::LibMeshInit> LMI;
-extern libMesh::Parallel::Communicator* libmesh_comm;
+extern const libMesh::Parallel::Communicator* libmesh_comm;
 #endif
 
 // Boolean flags
diff --git a/src/settings.cpp b/src/settings.cpp
index 4a2b3432db..d54543f728 100644
--- a/src/settings.cpp
+++ b/src/settings.cpp
@@ -39,7 +39,7 @@ namespace settings {
 
 #ifdef LIBMESH
 std::unique_ptr<libMesh::LibMeshInit> LMI;
-libMesh::Parallel::Communicator* libmesh_comm;
+const libMesh::Parallel::Communicator* libmesh_comm;
 #endif
 
 // Default values for boolean flags