diff --git a/src/EFF/fix_nh_eff.cpp b/src/EFF/fix_nh_eff.cpp
index a569932000..6e8e2c68fa 100644
--- a/src/EFF/fix_nh_eff.cpp
+++ b/src/EFF/fix_nh_eff.cpp
@@ -16,7 +16,6 @@
    Contributing author: Andres Jaramillo-Botero (Caltech)
 ------------------------------------------------------------------------- */
 
-
 #include "fix_nh_eff.h"
 
 #include "atom.h"
@@ -62,7 +61,7 @@ void FixNHEff::nve_v()
     if (mask[i] & groupbit) {
       if (abs(spin[i])==1) {
         dtfm = dtf / mass[type[i]];
-        ervel[i] = dtfm * erforce[i] / mefactor;
+        ervel[i] += dtfm * erforce[i] / mefactor;
       }
     }
   }
@@ -79,15 +78,26 @@ void FixNHEff::nve_x()
   FixNH::nve_x();
 
   double *eradius = atom->eradius;
+  double *erforce = atom->erforce;
   double *ervel = atom->ervel;
+  double *mass = atom->mass;
+  int *type = atom->type;
   int *spin = atom->spin;
   int *mask = atom->mask;
   int nlocal = atom->nlocal;
   if (igroup == atom->firstgroup) nlocal = atom->nfirst;
 
+  double mefactor = domain->dimension/4.0;
+  double dtfm;
+
   for (int i = 0; i < nlocal; i++)
-    if (mask[i] & groupbit)
-      if (abs(spin[i])==1) eradius[i] += dtv * ervel[i];
+    if (mask[i] & groupbit) {
+      dtfm = dtf / mass[type[i]];
+      if (abs(spin[i])==1) {
+        ervel[i] += dtfm * erforce[i] / mefactor;
+        eradius[i] += dtv * ervel[i];
+      }
+    }
 }
 
 /* ----------------------------------------------------------------------