diff --git a/CMakeLists.txt b/CMakeLists.txt
index e2506dd04..dc0654760 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -48,6 +48,12 @@ if((CMAKE_BUILD_TYPE STREQUAL "Debug") OR
   set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wall")
 endif()
 
+if (CMAKE_HOST_APPLE)
+    # Fix linker flags for OSX to use classic linker on XCode 15.0+:
+    # https://developer.apple.com/documentation/xcode-release-notes/xcode-15-release-notes#Linking
+    set(MPI_Fortran_LINK_FLAGS "${MPI_Fortran_LINK_FLAGS} -Wl,-ld_classic")
+endif()
+
 set(CAROM_VERSION_MAJOR "${PROJECT_VERSION_MAJOR}")
 set(CAROM_VERSION_MINOR "${PROJECT_VERSION_MINOR}")
 set(CAROM_VERSION_PATCHLEVEL "${PROJECT_VERSION_PATCH}")
diff --git a/examples/dmd/de_dg_advection_greedy.cpp b/examples/dmd/de_dg_advection_greedy.cpp
index d9e8045d9..ad7191b20 100644
--- a/examples/dmd/de_dg_advection_greedy.cpp
+++ b/examples/dmd/de_dg_advection_greedy.cpp
@@ -251,11 +251,8 @@ class FE_Evolution : public TimeDependentOperator
     virtual ~FE_Evolution();
 };
 
-// 1. Initialize MPI.
-MPI_Session mpi;
-int num_procs = mpi.WorldSize();
-int myid = mpi.WorldRank();
 //MFEM variables
+int num_procs, myid;
 const char *mesh_file = "../data/periodic-hexagon.mesh";
 int ser_ref_levels = 2;
 int par_ref_levels = 0;
@@ -367,7 +364,7 @@ double simulation()
         ode_solver = new SDIRK34Solver;
         break;
     default:
-        if (mpi.Root())
+        if (myid == 0)
         {
             cout << "Unknown ODE solver type: " << ode_solver_type << '\n';
         }
@@ -405,7 +402,7 @@ double simulation()
     ParFiniteElementSpace *fes = new ParFiniteElementSpace(pmesh, &fec);
 
     HYPRE_BigInt global_vSize = fes->GlobalTrueVSize();
-    if (mpi.Root())
+    if (myid == 0)
     {
         cout << "Number of unknowns: " << global_vSize << endl;
     }
@@ -549,11 +546,11 @@ double simulation()
         sout.open(vishost, visport);
         if (!sout)
         {
-            if (mpi.Root())
+            if (myid == 0)
                 cout << "Unable to connect to GLVis server at "
                      << vishost << ':' << visport << endl;
             visualization = false;
-            if (mpi.Root())
+            if (myid == 0)
             {
                 cout << "GLVis visualization disabled.\n";
             }
@@ -790,7 +787,7 @@ double simulation()
 
         if (done || ti % vis_steps == 0)
         {
-            if (mpi.Root())
+            if (myid == 0)
             {
                 cout << "time step: " << ti << ", time: " << t << endl;
             }
@@ -1141,6 +1138,10 @@ class RelativeDifferenceCostFunction : public CAROM::IOptimizable
 
 int main(int argc, char *argv[])
 {
+    // 1. Initialize MPI.
+    mfem::Mpi::Init();
+    num_procs = Mpi::WorldSize();
+    myid = Mpi::WorldRank();
 
     cout.precision(precision);
     // 2. Parse command-line options.
@@ -1251,19 +1252,19 @@ int main(int argc, char *argv[])
     args.Parse();
     if (!args.Good())
     {
-        if (mpi.Root())
+        if (myid == 0)
         {
             args.PrintUsage(cout);
         }
         return 1;
     }
-    if (mpi.Root())
+    if (myid == 0)
     {
         args.PrintOptions(cout);
     }
 
     Device device(device_config);
-    if (mpi.Root()) {
+    if (myid == 0) {
         device.Print();
     }
 
diff --git a/examples/dmd/dg_advection.cpp b/examples/dmd/dg_advection.cpp
index 6bb905ac0..1abdfef3d 100644
--- a/examples/dmd/dg_advection.cpp
+++ b/examples/dmd/dg_advection.cpp
@@ -233,9 +233,9 @@ class FE_Evolution : public TimeDependentOperator
 int main(int argc, char *argv[])
 {
     // 1. Initialize MPI.
-    MPI_Session mpi;
-    int num_procs = mpi.WorldSize();
-    int myid = mpi.WorldRank();
+    Mpi::Init();
+    const int num_procs = Mpi::WorldSize();
+    const int myid = Mpi::WorldRank();
 
     // 2. Parse command-line options.
     problem = 0;
@@ -322,19 +322,19 @@ int main(int argc, char *argv[])
     args.Parse();
     if (!args.Good())
     {
-        if (mpi.Root())
+        if (myid == 0)
         {
             args.PrintUsage(cout);
         }
         return 1;
     }
-    if (mpi.Root())
+    if (myid == 0)
     {
         args.PrintOptions(cout);
     }
 
     Device device(device_config);
-    if (mpi.Root()) {
+    if (myid == 0) {
         device.Print();
     }
 
@@ -385,7 +385,7 @@ int main(int argc, char *argv[])
         ode_solver = new SDIRK34Solver;
         break;
     default:
-        if (mpi.Root())
+        if (myid == 0)
         {
             cout << "Unknown ODE solver type: " << ode_solver_type << '\n';
         }
@@ -423,7 +423,7 @@ int main(int argc, char *argv[])
     ParFiniteElementSpace *fes = new ParFiniteElementSpace(pmesh, &fec);
 
     HYPRE_BigInt global_vSize = fes->GlobalTrueVSize();
-    if (mpi.Root())
+    if (myid == 0)
     {
         cout << "Number of unknowns: " << global_vSize << endl;
     }
@@ -563,11 +563,11 @@ int main(int argc, char *argv[])
         sout.open(vishost, visport);
         if (!sout)
         {
-            if (mpi.Root())
+            if (myid == 0)
                 cout << "Unable to connect to GLVis server at "
                      << vishost << ':' << visport << endl;
             visualization = false;
-            if (mpi.Root())
+            if (myid == 0)
             {
                 cout << "GLVis visualization disabled.\n";
             }
@@ -628,7 +628,7 @@ int main(int argc, char *argv[])
 
         if (done || ti % vis_steps == 0)
         {
-            if (mpi.Root())
+            if (myid == 0)
             {
                 cout << "time step: " << ti << ", time: " << t << endl;
             }
diff --git a/examples/dmd/dg_euler.cpp b/examples/dmd/dg_euler.cpp
index 6a4f85510..f88d03813 100644
--- a/examples/dmd/dg_euler.cpp
+++ b/examples/dmd/dg_euler.cpp
@@ -131,7 +131,9 @@ double max_char_speed;
 int main(int argc, char *argv[])
 {
     // 1. Initialize MPI.
-    MPI_Session mpi(argc, argv);
+    Mpi::Init();
+    const int num_procs = Mpi::WorldSize();
+    const int myid = Mpi::WorldRank();
 
     // 2. Parse command-line options.
     problem = 1;
@@ -197,12 +199,12 @@ int main(int argc, char *argv[])
     args.Parse();
     if (!args.Good())
     {
-        if (mpi.Root()) {
+        if (myid == 0) {
             args.PrintUsage(cout);
         }
         return 1;
     }
-    if (mpi.Root()) {
+    if (myid == 0) {
         args.PrintOptions(cout);
     }
 
@@ -234,7 +236,7 @@ int main(int argc, char *argv[])
         ode_solver = new RK6Solver;
         break;
     default:
-        if (mpi.Root())
+        if (myid == 0)
         {
             cout << "Unknown ODE solver type: " << ode_solver_type << '\n';
         }
@@ -273,7 +275,7 @@ int main(int argc, char *argv[])
     MFEM_ASSERT(fes.GetOrdering() == Ordering::byNODES, "");
 
     HYPRE_BigInt glob_size = vfes.GlobalTrueVSize();
-    if (mpi.Root()) {
+    if (myid == 0) {
         cout << "Number of unknowns: " << glob_size << endl;
     }
 
@@ -299,7 +301,7 @@ int main(int argc, char *argv[])
     // Output the initial solution.
     {
         ostringstream mesh_name;
-        mesh_name << "vortex-mesh." << setfill('0') << setw(6) << mpi.WorldRank();
+        mesh_name << "vortex-mesh." << setfill('0') << setw(6) << myid;
         ofstream mesh_ofs(mesh_name.str().c_str());
         mesh_ofs.precision(precision);
         mesh_ofs << pmesh;
@@ -309,7 +311,7 @@ int main(int argc, char *argv[])
             ParGridFunction uk(&fes, u_block.GetBlock(k));
             ostringstream sol_name;
             sol_name << "vortex-" << k << "-init."
-                     << setfill('0') << setw(6) << mpi.WorldRank();
+                     << setfill('0') << setw(6) << myid;
             ofstream sol_ofs(sol_name.str().c_str());
             sol_ofs.precision(precision);
             sol_ofs << uk;
@@ -342,19 +344,19 @@ int main(int argc, char *argv[])
         sout.open(vishost, visport);
         if (!sout)
         {
-            if (mpi.Root())
+            if (myid == 0)
             {
                 cout << "Unable to connect to GLVis server at "
                      << vishost << ':' << visport << endl;
             }
             visualization = false;
-            if (mpi.Root()) {
+            if (myid == 0) {
                 cout << "GLVis visualization disabled.\n";
             }
         }
         else
         {
-            sout << "parallel " << mpi.WorldSize() << " " << mpi.WorldRank() << "\n";
+            sout << "parallel " << num_procs << " " << myid << "\n";
             sout.precision(precision);
             sout << "solution\n" << pmesh << mom;
             sout << flush;
@@ -486,14 +488,14 @@ int main(int argc, char *argv[])
 
         if (done || ti % vis_steps == 0)
         {
-            if (mpi.Root())
+            if (myid == 0)
             {
                 cout << "time step: " << ti << ", time: " << t << endl;
             }
             if (visualization)
             {
                 MPI_Barrier(pmesh.GetComm());
-                sout << "parallel " << mpi.WorldSize() << " " << mpi.WorldRank() << "\n";
+                sout << "parallel " << num_procs << " " << myid << "\n";
                 sout << "solution\n" << pmesh << mom << flush;
             }
             if (visit)
@@ -506,7 +508,7 @@ int main(int argc, char *argv[])
     }
 
     tic_toc.Stop();
-    if (mpi.Root()) {
+    if (myid == 0) {
         cout << " done, " << tic_toc.RealTime() << "s." << endl;
     }
 
@@ -517,7 +519,7 @@ int main(int argc, char *argv[])
         ParGridFunction uk(&fes, u_block.GetBlock(k));
         ostringstream sol_name;
         sol_name << "vortex-" << k << "-final."
-                 << setfill('0') << setw(6) << mpi.WorldRank();
+                 << setfill('0') << setw(6) << myid;
         ofstream sol_ofs(sol_name.str().c_str());
         sol_ofs.precision(precision);
         sol_ofs << uk;
@@ -527,13 +529,13 @@ int main(int argc, char *argv[])
     if (t_final == 2.0)
     {
         const double error = sol.ComputeLpError(2, u0);
-        if (mpi.Root()) {
+        if (myid == 0) {
             cout << "Solution error: " << error << endl;
         }
     }
 
     // 13. Calculate the DMD modes.
-    if (mpi.WorldRank() == 0 && rdim != -1 && ef != -1)
+    if (myid == 0 && rdim != -1 && ef != -1)
     {
         std::cout << "Both rdim and ef are set. ef will be ignored." << std::endl;
     }
@@ -542,7 +544,7 @@ int main(int argc, char *argv[])
 
     if (rdim != -1)
     {
-        if (mpi.WorldRank() == 0)
+        if (myid == 0)
         {
             std::cout << "Creating DMD with rdim: " << rdim << std::endl;
         }
@@ -553,7 +555,7 @@ int main(int argc, char *argv[])
     }
     else if (ef != -1)
     {
-        if (mpi.WorldRank() == 0)
+        if (myid == 0)
         {
             std::cout << "Creating DMD with energy fraction: " << ef << std::endl;
         }
@@ -575,7 +577,7 @@ int main(int argc, char *argv[])
     true_solution_e = u_block.GetBlock(3).GetData();
 
     // 14. Predict using DMD.
-    if (mpi.WorldRank() == 0)
+    if (myid == 0)
     {
         std::cout << "Predicting density, momentum, and energy using DMD" << std::endl;
     }
@@ -680,7 +682,7 @@ int main(int argc, char *argv[])
     double tot_true_solution_e_norm = sqrt(InnerProduct(MPI_COMM_WORLD,
                                            true_solution_e, true_solution_e));
 
-    if (mpi.WorldRank() == 0)
+    if (myid == 0)
     {
         std::cout << "Relative error of DMD density (dens) at t_final: " << t_final <<
                   " is " << tot_diff_norm_dens / tot_true_solution_dens_norm << std::endl;
diff --git a/examples/dmd/local_dw_csv.cpp b/examples/dmd/local_dw_csv.cpp
index 4dd83031a..9a79c6c16 100644
--- a/examples/dmd/local_dw_csv.cpp
+++ b/examples/dmd/local_dw_csv.cpp
@@ -59,9 +59,9 @@ int main(int argc, char *argv[])
     cout.precision(precision);
 
     // 1. Initialize MPI.
-    MPI_Session mpi;
-    int num_procs = mpi.WorldSize();
-    int myid = mpi.WorldRank();
+    Mpi::Init();
+    const int num_procs = Mpi::WorldSize();
+    const int myid = Mpi::WorldRank();
 
     // 2. Parse command-line options.
     bool train = true;
@@ -141,13 +141,13 @@ int main(int argc, char *argv[])
     args.Parse();
     if (!args.Good())
     {
-        if (mpi.Root())
+        if (myid == 0)
         {
             args.PrintUsage(cout);
         }
         return 1;
     }
-    if (mpi.Root())
+    if (myid == 0)
     {
         args.PrintOptions(cout);
     }
@@ -166,7 +166,7 @@ int main(int argc, char *argv[])
         outputPath += "/" + string(basename);
     }
 
-    if (mpi.Root()) {
+    if (myid == 0) {
         const char path_delim = '/';
         string::size_type pos = 0;
         do {
diff --git a/examples/dmd/local_tw_csv.cpp b/examples/dmd/local_tw_csv.cpp
index 976017f7d..d6356f260 100644
--- a/examples/dmd/local_tw_csv.cpp
+++ b/examples/dmd/local_tw_csv.cpp
@@ -76,9 +76,9 @@ int main(int argc, char *argv[])
     cout.precision(precision);
 
     // 1. Initialize MPI.
-    MPI_Session mpi;
-    int num_procs = mpi.WorldSize();
-    int myid = mpi.WorldRank();
+    Mpi::Init();
+    const int num_procs = Mpi::WorldSize();
+    const int myid = Mpi::WorldRank();
 
     // 2. Parse command-line options.
     bool train = true;
@@ -165,13 +165,13 @@ int main(int argc, char *argv[])
     args.Parse();
     if (!args.Good())
     {
-        if (mpi.Root())
+        if (myid == 0)
         {
             args.PrintUsage(cout);
         }
         return 1;
     }
-    if (mpi.Root())
+    if (myid == 0)
     {
         args.PrintOptions(cout);
     }
@@ -188,7 +188,7 @@ int main(int argc, char *argv[])
         outputPath += "/" + string(basename);
     }
 
-    if (mpi.Root()) {
+    if (myid == 0) {
         const char path_delim = '/';
         string::size_type pos = 0;
         do {
diff --git a/examples/dmd/parametric_dw_csv.cpp b/examples/dmd/parametric_dw_csv.cpp
index 7222ea85f..7ca9ce830 100644
--- a/examples/dmd/parametric_dw_csv.cpp
+++ b/examples/dmd/parametric_dw_csv.cpp
@@ -67,9 +67,9 @@ int main(int argc, char *argv[])
     cout.precision(precision);
 
     // 1. Initialize MPI.
-    MPI_Session mpi;
-    int num_procs = mpi.WorldSize();
-    int myid = mpi.WorldRank();
+    Mpi::Init();
+    const int num_procs = Mpi::WorldSize();
+    const int myid = Mpi::WorldRank();
 
     // 2. Parse command-line options.
     bool offline = false;
@@ -155,13 +155,13 @@ int main(int argc, char *argv[])
     args.Parse();
     if (!args.Good())
     {
-        if (mpi.Root())
+        if (myid == 0)
         {
             args.PrintUsage(cout);
         }
         return 1;
     }
-    if (mpi.Root())
+    if (myid == 0)
     {
         args.PrintOptions(cout);
     }
@@ -180,7 +180,7 @@ int main(int argc, char *argv[])
         outputPath += "/" + string(basename);
     }
 
-    if (mpi.Root()) {
+    if (myid == 0) {
         const char path_delim = '/';
         string::size_type pos = 0;
         do {
diff --git a/examples/dmd/parametric_tw_csv.cpp b/examples/dmd/parametric_tw_csv.cpp
index 9e6399a60..1b132f8d9 100644
--- a/examples/dmd/parametric_tw_csv.cpp
+++ b/examples/dmd/parametric_tw_csv.cpp
@@ -95,9 +95,9 @@ int main(int argc, char *argv[])
     cout.precision(precision);
 
     // 1. Initialize MPI.
-    MPI_Session mpi;
-    int num_procs = mpi.WorldSize();
-    int myid = mpi.WorldRank();
+    Mpi::Init();
+    const int num_procs = Mpi::WorldSize();
+    const int myid = Mpi::WorldRank();
 
     // 2. Parse command-line options.
     bool offline = false;
@@ -213,13 +213,13 @@ int main(int argc, char *argv[])
     args.Parse();
     if (!args.Good())
     {
-        if (mpi.Root())
+        if (myid == 0)
         {
             args.PrintUsage(cout);
         }
         return 1;
     }
-    if (mpi.Root())
+    if (myid == 0)
     {
         args.PrintOptions(cout);
     }
@@ -238,7 +238,7 @@ int main(int argc, char *argv[])
         outputPath += "/" + string(basename);
     }
 
-    if (mpi.Root()) {
+    if (myid == 0) {
         const char path_delim = '/';
         string::size_type pos = 0;
         do {
diff --git a/examples/prom/dg_advection_global_rom.cpp b/examples/prom/dg_advection_global_rom.cpp
index 18dc48ea0..ab06e3548 100644
--- a/examples/prom/dg_advection_global_rom.cpp
+++ b/examples/prom/dg_advection_global_rom.cpp
@@ -272,9 +272,9 @@ class FE_Evolution : public TimeDependentOperator
 int main(int argc, char *argv[])
 {
     // 1. Initialize MPI.
-    MPI_Session mpi;
-    int num_procs = mpi.WorldSize();
-    int myid = mpi.WorldRank();
+    Mpi::Init();
+    const int num_procs = Mpi::WorldSize();
+    const int myid = Mpi::WorldRank();
 
     // 2. Parse command-line options.
     problem = 3;
@@ -380,13 +380,13 @@ int main(int argc, char *argv[])
     args.Parse();
     if (!args.Good())
     {
-        if (mpi.Root())
+        if (myid == 0)
         {
             args.PrintUsage(cout);
         }
         return 1;
     }
-    if (mpi.Root())
+    if (myid == 0)
     {
         args.PrintOptions(cout);
     }
@@ -404,7 +404,7 @@ int main(int argc, char *argv[])
     }
 
     Device device(device_config);
-    if (mpi.Root()) {
+    if (myid == 0) {
         device.Print();
     }
 
@@ -455,7 +455,7 @@ int main(int argc, char *argv[])
         ode_solver = new SDIRK34Solver;
         break;
     default:
-        if (mpi.Root())
+        if (myid == 0)
         {
             cout << "Unknown ODE solver type: " << ode_solver_type << '\n';
         }
@@ -492,7 +492,7 @@ int main(int argc, char *argv[])
     ParFiniteElementSpace *fes = new ParFiniteElementSpace(pmesh, &fec);
 
     HYPRE_BigInt global_vSize = fes->GlobalTrueVSize();
-    if (mpi.Root())
+    if (myid == 0)
     {
         cout << "Number of unknowns: " << global_vSize << endl;
     }
@@ -639,11 +639,11 @@ int main(int argc, char *argv[])
         sout.open(vishost, visport);
         if (!sout)
         {
-            if (mpi.Root())
+            if (myid == 0)
                 cout << "Unable to connect to GLVis server at "
                      << vishost << ':' << visport << endl;
             visualization = false;
-            if (mpi.Root())
+            if (myid == 0)
             {
                 cout << "GLVis visualization disabled.\n";
             }
@@ -655,7 +655,7 @@ int main(int argc, char *argv[])
             sout << "solution\n" << *pmesh << *u;
             sout << "pause\n";
             sout << flush;
-            if (mpi.Root())
+            if (myid == 0)
                 cout << "GLVis visualization paused."
                      << " Press space (in the GLVis window) to resume it.\n";
         }
@@ -828,7 +828,7 @@ int main(int argc, char *argv[])
 
         if (done || ti % vis_steps == 0)
         {
-            if (mpi.Root())
+            if (myid == 0)
             {
                 cout << "time step: " << ti << ", time: " << t << endl;
             }
@@ -847,7 +847,7 @@ int main(int argc, char *argv[])
             {
                 if (online)
                 {
-                    if (mpi.Root())
+                    if (myid == 0)
                         cout << "WARNING: FOM lifting for visualization is slow." << endl;
 
                     CAROM::Vector u_hat_final_carom(u_hat->GetData(), u_hat->Size(), false);
diff --git a/examples/prom/dg_advection_local_rom_matrix_interp.cpp b/examples/prom/dg_advection_local_rom_matrix_interp.cpp
index 93f8236e7..abbe6621c 100644
--- a/examples/prom/dg_advection_local_rom_matrix_interp.cpp
+++ b/examples/prom/dg_advection_local_rom_matrix_interp.cpp
@@ -283,9 +283,9 @@ class FE_Evolution : public TimeDependentOperator
 int main(int argc, char *argv[])
 {
     // 1. Initialize MPI.
-    MPI_Session mpi;
-    int num_procs = mpi.WorldSize();
-    int myid = mpi.WorldRank();
+    Mpi::Init();
+    const int num_procs = Mpi::WorldSize();
+    const int myid = Mpi::WorldRank();
 
     // 2. Parse command-line options.
     problem = 3;
@@ -401,19 +401,19 @@ int main(int argc, char *argv[])
     args.Parse();
     if (!args.Good())
     {
-        if (mpi.Root())
+        if (myid == 0)
         {
             args.PrintUsage(cout);
         }
         return 1;
     }
-    if (mpi.Root())
+    if (myid == 0)
     {
         args.PrintOptions(cout);
     }
 
     Device device(device_config);
-    if (mpi.Root()) {
+    if (myid == 0) {
         device.Print();
     }
 
@@ -476,7 +476,7 @@ int main(int argc, char *argv[])
         ode_solver = new SDIRK34Solver;
         break;
     default:
-        if (mpi.Root())
+        if (myid == 0)
         {
             cout << "Unknown ODE solver type: " << ode_solver_type << '\n';
         }
@@ -516,7 +516,7 @@ int main(int argc, char *argv[])
     ParFiniteElementSpace *fes = new ParFiniteElementSpace(pmesh, &fec);
 
     HYPRE_BigInt global_vSize = fes->GlobalTrueVSize();
-    if (mpi.Root())
+    if (myid == 0)
     {
         cout << "Number of unknowns: " << global_vSize << endl;
     }
@@ -663,11 +663,11 @@ int main(int argc, char *argv[])
         sout.open(vishost, visport);
         if (!sout)
         {
-            if (mpi.Root())
+            if (myid == 0)
                 cout << "Unable to connect to GLVis server at "
                      << vishost << ':' << visport << endl;
             visualization = false;
-            if (mpi.Root())
+            if (myid == 0)
             {
                 cout << "GLVis visualization disabled.\n";
             }
@@ -679,7 +679,7 @@ int main(int argc, char *argv[])
             sout << "solution\n" << *pmesh << *u;
             sout << "pause\n";
             sout << flush;
-            if (mpi.Root())
+            if (myid == 0)
                 cout << "GLVis visualization paused."
                      << " Press space (in the GLVis window) to resume it.\n";
         }
@@ -937,7 +937,7 @@ int main(int argc, char *argv[])
 
         if (done || ti % vis_steps == 0)
         {
-            if (mpi.Root())
+            if (myid == 0)
             {
                 cout << "time step: " << ti << ", time: " << t << endl;
             }
diff --git a/scripts/setup.sh b/scripts/setup.sh
index fd0d86596..d263ab266 100755
--- a/scripts/setup.sh
+++ b/scripts/setup.sh
@@ -153,7 +153,6 @@ ROM_CFLAGS="${CFLAGS}"
 ROM_CXXFLAGS="${CXXFLAGS}"
 unset CFLAGS
 unset CXXFLAGS
-unset CPPFLAGS
 
 # Install MFEM
 cd $LIB_DIR
@@ -165,7 +164,7 @@ if [[ $BUILD_TYPE == "Debug" ]]; then
     if [[ $UPDATE_LIBS == "true" ]]; then
         cd mfem_debug
         git pull
-        make -j 8 pdebug BASE_FLAGS="${ROM_CFLAGS}" STATIC=NO SHARED=YES MFEM_USE_MPI=YES MFEM_USE_GSLIB=${MG} MFEM_USE_LAPACK=${MFEM_USE_LAPACK:-"NO"} MFEM_USE_METIS=YES MFEM_USE_METIS_5=YES METIS_DIR="$METIS_DIR" METIS_OPT="$METIS_OPT" METIS_LIB="$METIS_LIB" MFEM_USE_SUPERLU=${MFEM_USE_SUPERLU:-"NO"} SUPERLU_DIR="$SUPERLU_DIR" SUPERLU_OPT="$SUPERLU_OPT" SUPERLU_LIB="$SUPERLU_LIB"
+        make -j 8 pdebug CPPFLAGS="${ROM_CXXFLAGS}" STATIC=NO SHARED=YES MFEM_USE_MPI=YES MFEM_USE_GSLIB=${MG} MFEM_USE_LAPACK=${MFEM_USE_LAPACK:-"NO"} MFEM_USE_METIS=YES MFEM_USE_METIS_5=YES METIS_DIR="$METIS_DIR" METIS_OPT="$METIS_OPT" METIS_LIB="$METIS_LIB" MFEM_USE_SUPERLU=${MFEM_USE_SUPERLU:-"NO"} SUPERLU_DIR="$SUPERLU_DIR" SUPERLU_OPT="$SUPERLU_OPT" SUPERLU_LIB="$SUPERLU_LIB"
         check_result $? mfem-debug-installation
     fi
     cd $LIB_DIR
@@ -182,7 +181,7 @@ else
         # NOTE(kevin): v4.5.2-dev commit. This is the mfem version used by PyMFEM v4.5.2.0.
         # This version matching is required to support pylibROM-PyMFEM interface.
         git checkout 00b2a0705f647e17a1d4ffcb289adca503f28d42
-        make -j 8 parallel BASE_FLAGS="${ROM_CFLAGS}" STATIC=NO SHARED=YES MFEM_USE_MPI=YES MFEM_USE_GSLIB=${MG} MFEM_USE_LAPACK=${MFEM_USE_LAPACK:-"NO"} MFEM_USE_METIS=YES MFEM_USE_METIS_5=YES METIS_DIR="$METIS_DIR" METIS_OPT="$METIS_OPT" METIS_LIB="$METIS_LIB" MFEM_USE_SUPERLU=${MFEM_USE_SUPERLU:-"NO"} SUPERLU_DIR="$SUPERLU_DIR" SUPERLU_OPT="$SUPERLU_OPT" SUPERLU_LIB="$SUPERLU_LIB"
+        make -j 8 parallel CPPFLAGS="${ROM_CXXFLAGS}" STATIC=NO SHARED=YES MFEM_USE_MPI=YES MFEM_USE_GSLIB=${MG} MFEM_USE_LAPACK=${MFEM_USE_LAPACK:-"NO"} MFEM_USE_METIS=YES MFEM_USE_METIS_5=YES METIS_DIR="$METIS_DIR" METIS_OPT="$METIS_OPT" METIS_LIB="$METIS_LIB" MFEM_USE_SUPERLU=${MFEM_USE_SUPERLU:-"NO"} SUPERLU_DIR="$SUPERLU_DIR" SUPERLU_OPT="$SUPERLU_OPT" SUPERLU_LIB="$SUPERLU_LIB"
         check_result $? mfem-parallel-installation
     fi
     cd $LIB_DIR