diff --git a/src/ode_rk45.f90 b/src/ode_rk45.f90
index 49f5a04..1001a7e 100644
--- a/src/ode_rk45.f90
+++ b/src/ode_rk45.f90
@@ -389,6 +389,8 @@ end subroutine rkf45_d
 
   subroutine rkfs_d ( f, neqn, y, t, tout, relerr, abserr, iflag, yp, h, &
     f1, f2, f3, f4, f5, savre, savae, nfe, kop, init, jflag, kflag )
+
+    use my_mpi, only: is_MPI_parallel, max_allproc, min_allproc
   !
   !*******************************************************************************
   !
@@ -464,6 +466,7 @@ subroutine rkfs_d ( f, neqn, y, t, tout, relerr, abserr, iflag, yp, h, &
     double precision y(neqn)
     double precision yp(neqn)
     double precision ypk
+    double precision hminglob  ! YD
   !
   !  Check the input parameters.
   !
@@ -627,6 +630,12 @@ subroutine rkfs_d ( f, neqn, y, t, tout, relerr, abserr, iflag, yp, h, &
       end if
     end do
 
+    ! YD
+    if (is_MPI_parallel()) then
+      call min_allproc(h,hminglob)
+      h = hminglob
+    endif
+
     if ( toln <= 0.0D+00 ) then
       h = 0.0D+00
     end if
@@ -773,6 +782,12 @@ subroutine rkfs_d ( f, neqn, y, t, tout, relerr, abserr, iflag, yp, h, &
 
     end do
 
+  ! YD: MPI sync max err, min overhead
+    if (is_MPI_parallel()) then
+      call max_allproc(eeoet, hminglob)
+      eeoet = hminglob
+    endif
+
     esttol = abs ( h ) * eeoet * scale / 752400.0D+00
 
     ! SEISMIC: if the integration result contains NaNs,
diff --git a/src/parallel.f90 b/src/parallel.f90
index 0117c58..4c82ced 100644
--- a/src/parallel.f90
+++ b/src/parallel.f90
@@ -15,7 +15,7 @@ module my_mpi
             my_mpi_tag, my_mpi_rank, my_mpi_NPROCS, is_mpi_parallel, &
             is_mpi_master, gather_allv, gather_allvdouble, &
             gather_allvdouble_root, gather_allvi_root, gather_alli, &
-            synchronize_all, sum_allreduce, max_allproc
+            synchronize_all, sum_allreduce, max_allproc, min_allproc
 
 contains
 
@@ -28,10 +28,6 @@ subroutine init_mpi()
 
   call MPI_INIT(ier)
   if (ier /= 0 ) stop 'Error initializing MPI'
-  call MPI_COMM_RANK(MPI_COMM_WORLD,MY_RANK,ier)
-  if (ier /= 0 ) stop 'Error getting MPI rank'
-  call MPI_COMM_SIZE(MPI_COMM_WORLD,NPROCS,ier)
-  if (ier /= 0 ) stop 'Error getting MPI world size'
 
   if (NPROCS<2) call MPI_FINALIZE(ier)
   if (MY_RANK==0) write(6,*) 'Number of processors = ',NPROCS
@@ -234,4 +230,16 @@ subroutine max_allproc(sendbuf, recvbuf)
   end subroutine max_allproc
 
 !-------------------------------------------------------------------------------------------------
+!
+  subroutine min_allproc(sendbuf, recvbuf)
+
+  double precision :: sendbuf, recvbuf
+  integer ier
+
+  call MPI_ALLREDUCE(sendbuf,recvbuf,1,MPI_DOUBLE_PRECISION,MPI_MIN,MPI_COMM_WORLD,ier)
+
+  end subroutine min_allproc
+
+!-------------------------------------------------------------------------------------------------
+
 end module my_mpi