diff --git a/src/fix_nh.cpp b/src/fix_nh.cpp
index 9d88d8f0fb..06a134bc17 100644
--- a/src/fix_nh.cpp
+++ b/src/fix_nh.cpp
@@ -1580,10 +1580,38 @@ void FixNH::reset_dt()
       p_freq_max = MAX(p_freq_max,p_freq[4]);
       p_freq_max = MAX(p_freq_max,p_freq[5]);
     }
+
+    double kt = boltz * t_target;
+    double nkt = atom->natoms * kt;
+
+    for (int i = 0; i < 3; i++)
+      if (p_flag[i])
+	omega_mass[i] = nkt/(p_freq[i]*p_freq[i]);
+
+    if (pstyle == TRICLINIC) {
+      for (int i = 3; i < 6; i++)
+	if (p_flag[i]) omega_mass[i] = nkt/(p_freq[i]*p_freq[i]);
+    }
+
+  // masses and initial forces on barostat thermostat variables
+
+    if (mpchain) {
+      etap_mass[0] = boltz * t_target / (p_freq_max*p_freq_max);
+      for (int ich = 1; ich < mpchain; ich++)
+	etap_mass[ich] = boltz * t_target / (p_freq_max*p_freq_max);
+      for (int ich = 1; ich < mpchain; ich++)
+	etap_dotdot[ich] = 
+	  (etap_mass[ich-1]*etap_dot[ich-1]*etap_dot[ich-1] -
+	   boltz * t_target) / etap_mass[ich];
+    }
+
     pdrag_factor = 1.0 - (update->dt * p_freq_max * drag / nc_pchain);
   }
 
   if (tstat_flag)
+    eta_mass[0] = tdof * boltz * t_target / (t_freq*t_freq);
+    for (int ich = 1; ich < mtchain; ich++)
+      eta_mass[ich] = boltz * t_target / (t_freq*t_freq);
     tdrag_factor = 1.0 - (update->dt * t_freq * drag / nc_tchain);
 }