diff --git a/src/ZSOLVER/tensorproductmultigrid_Source/communication.f90 b/src/ZSOLVER/tensorproductmultigrid_Source/communication.f90
index 85ee35626e2c29bb1c63ed1fefb159276da72637..3d33cf8b80fac89c56298a4a805e7074df25ac36 100644
--- a/src/ZSOLVER/tensorproductmultigrid_Source/communication.f90
+++ b/src/ZSOLVER/tensorproductmultigrid_Source/communication.f90
@@ -1918,7 +1918,7 @@ contains
                 MPI_DOUBLE_PRECISION,source_rank,recv_tag,MPI_COMM_HORIZ,stat,ierr)
            !$acc end host_data
            !$acc parallel loop collapse(3)
-           do concurrent (ii=1:a_n,ij=1:a_n,ik=1:nz+2)
+           do concurrent (ii=1:b_n,ij=1:b_n,ik=1:nz+2)
               zb_st(ii,ij,ik-1) = ztab_interiorT_ne_m_haloTout(ii,ij,ik)
            end do
 #else
@@ -1950,7 +1950,7 @@ contains
                 MPI_DOUBLE_PRECISION,source_rank,recv_tag,MPI_COMM_HORIZ,stat,ierr)
            !$acc end host_data
            !$acc parallel loop collapse(3)
-           do concurrent (ii=1:a_n,ij=1:a_n,ik=1:nz+2)
+           do concurrent (ii=1:b_n,ij=1:b_n,ik=1:nz+2)
               zb_st(ii,ij,ik-1) = ztab_interiorT_sw_m_haloTout(ii,ij,ik)
            end do
 #else
@@ -1982,7 +1982,7 @@ contains
                 MPI_DOUBLE_PRECISION,source_rank,recv_tag,MPI_COMM_HORIZ,stat,ierr)
            !$acc end host_data
            !$acc parallel loop collapse(3)
-           do concurrent (ii=1:a_n,ij=1:a_n,ik=1:nz+2)
+           do concurrent (ii=1:b_n,ij=1:b_n,ik=1:nz+2)
               zb_st(ii,ij,ik-1) = ztab_interiorT_se_m_haloTout(ii,ij,ik)
            end do           
 #else