diff --git a/patches/gromacs-5.1.2.diff/src/programs/mdrun/md.cpp b/patches/gromacs-5.1.2.diff/src/programs/mdrun/md.cpp
index 7af01c2a57fc05aea99fb6c7a5bfa41b91773283..430c006c8e6bcf97c73372eddc53f349d8d64922 100644
--- a/patches/gromacs-5.1.2.diff/src/programs/mdrun/md.cpp
+++ b/patches/gromacs-5.1.2.diff/src/programs/mdrun/md.cpp
@@ -1096,7 +1096,8 @@ double do_md(FILE *fplog, t_commrec *cr, int nfile, const t_filenm fnm[],
                        GMX_FORCE_VIRIAL |
                        GMX_FORCE_ENERGY |
                        GMX_FORCE_DHDL |
-                       GMX_FORCE_NS);
+                       GMX_FORCE_NS |
+                       ( ( fr->bTwinRange && do_per_step(step, ir->nstcalclr) ) ? GMX_FORCE_DO_LR :0) );
           plumed_cmd(plumedmain,"GREX cacheLocalUSwap",&hrex_enerd->term[F_EPOT]);
           sfree(hrex_enerd);
 
diff --git a/patches/gromacs-5.1.2.diff/src/programs/mdrun/repl_ex.cpp b/patches/gromacs-5.1.2.diff/src/programs/mdrun/repl_ex.cpp
index 63eac8236921fb0dbc752d02315f01aea7a09acf..e799bc66964a891d20d901b8fd0e543a9cfc03a3 100644
--- a/patches/gromacs-5.1.2.diff/src/programs/mdrun/repl_ex.cpp
+++ b/patches/gromacs-5.1.2.diff/src/programs/mdrun/repl_ex.cpp
@@ -895,6 +895,11 @@ static real calc_delta(FILE *fplog, gmx_bool bPrint, struct gmx_repl_ex *re, int
     {
         fprintf(fplog, "Repl %d <-> %d  dE_term = %10.3e (kT)\n", a, b, delta);
     }
+
+/* this is necessary because with plumed HREX the energy contribution is
+   already taken into account */
+    if(plumed_hrex) delta=0.0;
+
     if (re->bNPT)
     {
         /* revist the calculation for 5.0.  Might be some improvements. */
@@ -1117,9 +1122,6 @@ test_for_replica_exchange(FILE                 *fplog,
             if (i % 2 == m)
             {
                 delta = calc_delta(fplog, bPrint, re, a, b, a, b);
-/* this is necessary because with plumed HREX the energy contribution is
-   already taken into account */
-                if(plumed_hrex) delta=0.0;
 
                 /* PLUMED */
                 if(plumedswitch){
diff --git a/user-doc/tutorials/hrex.txt b/user-doc/tutorials/hrex.txt
index 4e18296e7a49b27498d2fef2d5b1e7ad24ceca82..b3c4f6f754d853899499e9a9d5c3401f9f41d8a1 100644
--- a/user-doc/tutorials/hrex.txt
+++ b/user-doc/tutorials/hrex.txt
@@ -132,13 +132,22 @@ Notice that total cell could be charged. This happens whenever the scaled portio
 is not neutral. There should be no problem in this. When used with pbc, GROMACS
 will add a compensating background.
 
-Suggested checks:
+Suggested check:
 - Try with several identical force fields (hardcode the same lambda for all replicas in the
   script above) and different seed/starting point. Acceptance should be 1.0
 
+Notice that when you run with GPUs acceptance could be different from 1.0.
+The reason is that to compute the acceptance GROMACS is sending the coordinates to the neighboring
+replicas which then recompute energy. If all the tpr files are identical, one would expect
+energy to be identically to the originally computed one. However, calculations
+made with GPUs are typically not reproducible to machine precision. For a large system, even
+an error in the total energy for the last significant digit could be on the order of a kJ.
+This results in practice in a lower acceptance. The error induced on the final ensemble is
+expected to be very small.
+
+
 Warnings:
 - Topologies should have the same number of atoms, same masses and same constraint topology
-- Acceptance is not computed correctly if rcoulomb!=rvdw.
 - Choose neighbor list update (nstlist) that divides replex. Notice that running with GPUs
   GROMACS is going to change nstlist automatically, be sure that it still divides replex.
 - Option -hrex requires also option -plumed. If you do not care about plumed, just provide an empty