diff --git a/GNUmakefile.in b/GNUmakefile.in
index a13bc1cfff..e04b3da012 100644
--- a/GNUmakefile.in
+++ b/GNUmakefile.in
@@ -12,6 +12,9 @@ ifeq ($(USE_FORTRAN_INTERFACE),TRUE)
 endif
 ifeq ($(USE_LINEAR_SOLVERS),TRUE)
    Pdirs += LinearSolvers/MLMG LinearSolvers/C_CellMG
+   ifeq ($(USE_FORTRAN_INTERFACE),TRUE)
+     Pdirs += F_Interfaces/LinearSolvers
+   endif
 endif
 Ppack := $(foreach dir, $(Pdirs), $(AMREX_HOME)/Src/$(dir)/Make.package)
 include $(Ppack)
diff --git a/Src/Base/AMReX_ParallelDescriptor.cpp b/Src/Base/AMReX_ParallelDescriptor.cpp
index c31a2cc44a..b2c7a3ecfa 100644
--- a/Src/Base/AMReX_ParallelDescriptor.cpp
+++ b/Src/Base/AMReX_ParallelDescriptor.cpp
@@ -460,6 +460,8 @@ ParallelDescriptor::EndParallel ()
       m_comm_all = MPI_COMM_NULL;
     }
 
+    ParallelDescriptor::SeqNum(2, m_MinTag);
+
     if (call_mpi_finalize) {
         BL_MPI_REQUIRE( MPI_Finalize() );
     }
diff --git a/Tests/ThirdPartyLib/bar.F90 b/Tests/ThirdPartyLib/bar.F90
index caf24b2601..57e5a51d71 100644
--- a/Tests/ThirdPartyLib/bar.F90
+++ b/Tests/ThirdPartyLib/bar.F90
@@ -1,6 +1,7 @@
 
 subroutine bar (comm) bind(c)
   use amrex_base_module
+  implicit none
   integer, intent(in), value :: comm
 
   integer :: rank, ierr
@@ -11,6 +12,8 @@ subroutine bar (comm) bind(c)
      print *, "bar: AMReX Fortran has been initialized."
   end if
 
+  call fsolve()
+
   call amrex_finalize()
 
   ! After amrex_finalize(), amrex can no longer be used.
@@ -19,4 +22,75 @@ subroutine bar (comm) bind(c)
      print *, "bar: AMReX Fortran has been finalized."
   end if
   
+contains
+
+  subroutine fsolve
+    use amrex_linear_solver_module
+
+    type(amrex_box) :: domain, bx
+    type(amrex_geometry) :: geom
+    type(amrex_boxarray) :: grids
+    type(amrex_distromap) :: dm
+    type(amrex_multifab) :: rhs, phi
+    type(amrex_mfiter) :: mfi
+    real(amrex_real), pointer :: prhs(:,:,:,:)
+    integer :: lo(4), hi(4), i, j, k
+    real(amrex_real) :: r, error
+    type(amrex_poisson) :: poisson
+    type(amrex_multigrid) :: multigrid
+
+    call amrex_geometry_set_coord_sys(0)  ! Cartesian
+    call amrex_geometry_set_prob_domain([0._amrex_real,0._amrex_real,0._amrex_real], &
+         &                              [1._amrex_real,1._amrex_real,1._amrex_real])
+    call amrex_geometry_set_periodic([.true., .true., .true.])
+
+    domain = amrex_box([0,0,0], [63,63,63])  ! # of cells
+
+    call amrex_geometry_build(geom, domain)
+    call amrex_boxarray_build(grids, domain)
+    call grids % maxSize(32)
+    call amrex_distromap_build(dm, grids)
+    call amrex_multifab_build(rhs, grids, dm, nc=1, ng=0)
+    call amrex_multifab_build(phi, grids, dm, nc=1, ng=1)
+
+    ! set right hand side to random numbers
+    call amrex_mfiter_build(mfi, rhs)
+    do while (mfi%next())
+       bx = mfi%tilebox()
+       prhs => rhs%dataptr(mfi)
+       lo = lbound(prhs)
+       hi = ubound(prhs)
+       do k = lo(3), hi(3)
+          do j = lo(2), hi(2)
+             do i = lo(1), hi(1)
+                call random_number(r)
+                prhs(i,j,k,1) = r
+             end do
+          end do
+       end do
+    end do
+    call amrex_mfiter_destroy(mfi)
+
+    call phi % setVal(0.0_amrex_real) ! intial guess
+
+    call amrex_poisson_build(poisson, [geom], [grids], [dm])
+    call poisson % set_domain_bc([amrex_lo_periodic,amrex_lo_periodic,amrex_lo_periodic], &
+         &                       [amrex_lo_periodic,amrex_lo_periodic,amrex_lo_periodic]);
+    call poisson % set_level_bc(0, phi)
+
+    call amrex_multigrid_build(multigrid, poisson)
+    call multigrid % set_verbose(1)
+
+    error = multigrid % solve([phi], [rhs], 1.e-10_amrex_real, 0.0_amrex_real)
+
+    call amrex_poisson_destroy(poisson)
+    call amrex_multigrid_destroy(multigrid)
+
+    call amrex_multifab_destroy(rhs)
+    call amrex_multifab_destroy(phi)
+    call amrex_geometry_destroy(geom)
+    call amrex_boxarray_destroy(grids)
+    call amrex_distromap_destroy(dm)
+  end subroutine fsolve
+
 end subroutine bar
diff --git a/Tests/ThirdPartyLib/foo.cpp b/Tests/ThirdPartyLib/foo.cpp
index e268f682ed..b183d1ca85 100644
--- a/Tests/ThirdPartyLib/foo.cpp
+++ b/Tests/ThirdPartyLib/foo.cpp
@@ -2,6 +2,8 @@
 #include <AMReX.H>
 #include <AMReX_Print.H>
 
+void csolve ();
+
 extern "C"
 {
     void foo(MPI_Comm comm)
@@ -9,6 +11,8 @@ extern "C"
         amrex::Initialize(comm);
         
         amrex::Print() << " foo: AMReX C++ has been initialized.\n";
+
+        csolve();
         
         amrex::Finalize();
 
@@ -20,3 +24,47 @@ extern "C"
         }
     }
 }
+
+#include <AMReX_MLPoisson.H>
+#include <AMReX_MLMG.H>
+
+using namespace amrex;
+
+void csolve ()
+{
+    RealBox rb({0.,0.,0.}, {1.,1.,1.}); // physical domain size
+    std::array<int,3> is_periodic{1,1,1}; // periodic bc
+    Geometry::Setup(&rb, 0, is_periodic.data());
+
+    Box domain({0,0,0}, {63,63,63});  // # of cells
+
+    Geometry geom(domain);
+
+    BoxArray grids(domain);
+    grids.maxSize(32);
+
+    DistributionMapping dm(grids);
+
+    MultiFab rhs(grids, dm, 1, 0);
+    MultiFab phi(grids, dm, 1, 1);
+
+    // set right hand side to some random numbers
+    for (MFIter mfi(rhs); mfi.isValid(); ++mfi)
+    {
+        auto& fab = rhs[mfi];
+        fab.ForEach(fab.box(), 0, 1, [] (Real& rho) { rho = Random(); });
+    }
+
+    // set initial guess of potential to zero
+    phi.setVal(0.0);
+
+    MLPoisson mlpoisson({geom}, {grids}, {dm});
+
+    mlpoisson.setDomainBC({LinOpBCType::Periodic,LinOpBCType::Periodic,LinOpBCType::Periodic},
+                          {LinOpBCType::Periodic,LinOpBCType::Periodic,LinOpBCType::Periodic});                        
+    mlpoisson.setLevelBC(0,nullptr);
+   
+    MLMG mlmg(mlpoisson);
+    mlmg.setVerbose(1);
+    mlmg.solve({&phi}, {&rhs}, 1.e-10, 0.0);
+}