diff --git a/physics/mp_thompson.F90 b/physics/mp_thompson.F90
index 1d235c3e6..f4720eb72 100644
--- a/physics/mp_thompson.F90
+++ b/physics/mp_thompson.F90
@@ -565,7 +565,7 @@ subroutine mp_thompson_run(ncol, nlev, con_g, con_rd,        &
             if (do_effective_radii) then
                call mp_gt_driver(qv=qv, qc=qc, qr=qr, qi=qi, qs=qs, qg=qg, ni=ni, nr=nr,        &
                                  nc=nc, nwfa=nwfa, nifa=nifa, nwfa2d=nwfa2d, nifa2d=nifa2d,     &
-                                 tt=tgrs, p=prsl, w=w, dz=dz, dt_in=dtp,                        &
+                                 tt=tgrs, p=prsl, w=w, dz=dz, dt_in=dtstep,                     &
                                  rainnc=rain_mp, rainncv=delta_rain_mp,                         &
                                  snownc=snow_mp, snowncv=delta_snow_mp,                         &
                                  icenc=ice_mp, icencv=delta_ice_mp,                             &
@@ -586,7 +586,7 @@ subroutine mp_thompson_run(ncol, nlev, con_g, con_rd,        &
             else
                call mp_gt_driver(qv=qv, qc=qc, qr=qr, qi=qi, qs=qs, qg=qg, ni=ni, nr=nr,        &
                                  nc=nc, nwfa=nwfa, nifa=nifa, nwfa2d=nwfa2d, nifa2d=nifa2d,     &
-                                 tt=tgrs, p=prsl, w=w, dz=dz, dt_in=dtp,                        &
+                                 tt=tgrs, p=prsl, w=w, dz=dz, dt_in=dtstep,                     &
                                  rainnc=rain_mp, rainncv=delta_rain_mp,                         &
                                  snownc=snow_mp, snowncv=delta_snow_mp,                         &
                                  icenc=ice_mp, icencv=delta_ice_mp,                             &
@@ -607,7 +607,7 @@ subroutine mp_thompson_run(ncol, nlev, con_g, con_rd,        &
          else
             if (do_effective_radii) then
                call mp_gt_driver(qv=qv, qc=qc, qr=qr, qi=qi, qs=qs, qg=qg, ni=ni, nr=nr,        &
-                                 tt=tgrs, p=prsl, w=w, dz=dz, dt_in=dtp,                        &
+                                 tt=tgrs, p=prsl, w=w, dz=dz, dt_in=dtstep,                     &
                                  rainnc=rain_mp, rainncv=delta_rain_mp,                         &
                                  snownc=snow_mp, snowncv=delta_snow_mp,                         &
                                  icenc=ice_mp, icencv=delta_ice_mp,                             &
@@ -627,7 +627,7 @@ subroutine mp_thompson_run(ncol, nlev, con_g, con_rd,        &
                                  first_time_step=first_time_step, errmsg=errmsg, errflg=errflg)
             else
                call mp_gt_driver(qv=qv, qc=qc, qr=qr, qi=qi, qs=qs, qg=qg, ni=ni, nr=nr,        &
-                                 tt=tgrs, p=prsl, w=w, dz=dz, dt_in=dtp,                        &
+                                 tt=tgrs, p=prsl, w=w, dz=dz, dt_in=dtstep,                     &
                                  rainnc=rain_mp, rainncv=delta_rain_mp,                         &
                                  snownc=snow_mp, snowncv=delta_snow_mp,                         &
                                  icenc=ice_mp, icencv=delta_ice_mp,                             &