diff --git a/Source/BoundaryConditions/ABLMost.cpp b/Source/BoundaryConditions/ABLMost.cpp
index 056414918..c88ec7bd9 100644
--- a/Source/BoundaryConditions/ABLMost.cpp
+++ b/Source/BoundaryConditions/ABLMost.cpp
@@ -400,8 +400,8 @@ ABLMost::compute_most_bcs (const int& lev,
                     n = RhoQ1_comp;
                     ParallelFor(b2d, [=] AMREX_GPU_DEVICE (int i, int j, int k)
                     {
-                        Real dz  = (zphys_arr) ? ( zphys_arr(i,j,klo  ) - zphys_arr(i,j,klo-1) ) : dxInv[2];
-                        Real dz1 = (zphys_arr) ? ( zphys_arr(i,j,klo+1) - zphys_arr(i,j,klo  ) ) : dxInv[2];
+                        Real dz  = (zphys_arr) ? ( zphys_arr(i,j,klo  ) - zphys_arr(i,j,klo-1) ) : dz_no_terrain;
+                        Real dz1 = (zphys_arr) ? ( zphys_arr(i,j,klo+1) - zphys_arr(i,j,klo  ) ) : dz_no_terrain;
                         Real Qflux = flux_comp.compute_q_flux(i, j, k, n, icomp, dz, dz1, exp_most, eta_arr,
                                                               cons_arr, velx_arr, vely_arr,
                                                               umm_arr, qm_arr, u_star_arr, q_star_arr, t_surf_arr,