diff --git a/src/fix.cpp b/src/fix.cpp
index e6e8a292b9..80fa00f4b3 100644
--- a/src/fix.cpp
+++ b/src/fix.cpp
@@ -31,7 +31,7 @@ int Fix::instance_total = 0;
 
 /* ---------------------------------------------------------------------- */
 
-Fix::Fix(LAMMPS *lmp, int narg, char **arg) : 
+Fix::Fix(LAMMPS *lmp, int narg, char **arg) :
   Pointers(lmp),
   id(NULL), style(NULL), extlist(NULL), vector_atom(NULL), array_atom(NULL),
   vector_local(NULL), array_local(NULL), eatom(NULL), vatom(NULL)
@@ -61,6 +61,7 @@ Fix::Fix(LAMMPS *lmp, int narg, char **arg) :
   force_reneighbor = 0;
   box_change_size = box_change_shape = box_change_domain = 0;
   thermo_energy = 0;
+  thermo_virial = 0;
   rigid_flag = 0;
   peatom_flag = 0;
   virial_flag = 0;
@@ -140,8 +141,20 @@ void Fix::modify_params(int narg, char **arg)
     } else if (strcmp(arg[iarg],"energy") == 0) {
       if (iarg+2 > narg) error->all(FLERR,"Illegal fix_modify command");
       if (strcmp(arg[iarg+1],"no") == 0) thermo_energy = 0;
-      else if (strcmp(arg[iarg+1],"yes") == 0) thermo_energy = 1;
-      else error->all(FLERR,"Illegal fix_modify command");
+      else if (strcmp(arg[iarg+1],"yes") == 0) {
+        if (!(THERMO_ENERGY & setmask()))
+          error->all(FLERR,"Illegal fix_modify command");
+        thermo_energy = 1;
+      } else error->all(FLERR,"Illegal fix_modify command");
+      iarg += 2;
+    } else if (strcmp(arg[iarg],"virial") == 0) {
+      if (iarg+2 > narg) error->all(FLERR,"Illegal fix_modify command");
+      if (strcmp(arg[iarg+1],"no") == 0) thermo_virial = 0;
+      else if (strcmp(arg[iarg+1],"yes") == 0) {
+        if (virial_flag == 0)
+          error->all(FLERR,"Illegal fix_modify command");
+        thermo_virial = 1;
+      } else error->all(FLERR,"Illegal fix_modify command");
       iarg += 2;
     } else if (strcmp(arg[iarg],"respa") == 0) {
       if (iarg+2 > narg) error->all(FLERR,"Illegal fix_modify command");
@@ -214,15 +227,22 @@ void Fix::ev_setup(int eflag, int vflag)
 }
 
 /* ----------------------------------------------------------------------
-   setup for virial computation
-   see integrate::ev_set() for values of vflag (0-6)
-   fixes call this if use v_tally()
+   if thermo_virial is on:
+     setup for virial computation
+     see integrate::ev_set() for values of vflag (0-6)
+     fixes call this if use v_tally()
+   else: set evflag=0
 ------------------------------------------------------------------------- */
 
 void Fix::v_setup(int vflag)
 {
   int i,n;
 
+  if (!thermo_virial) {
+    evflag = 0;
+    return;
+  }
+
   evflag = 1;
 
   vflag_global = vflag % 4;
@@ -316,3 +336,58 @@ void Fix::v_tally(int n, int *list, double total, double *v)
     }
   }
 }
+
+/* ----------------------------------------------------------------------
+   tally virial into global and per-atom accumulators
+   i = local index of atom
+   v = total virial for the interaction
+   increment global virial by v
+   increment per-atom virial by v
+   this method can be used when fix computes forces in post_force()
+   and the force depends on a distance to some external object
+     e.g. fix wall/lj93: compute virial only on owned atoms
+------------------------------------------------------------------------- */
+
+void Fix::v_tally(int i, double *v)
+{
+
+  if (vflag_global) {
+    virial[0] += v[0];
+    virial[1] += v[1];
+    virial[2] += v[2];
+    virial[3] += v[3];
+    virial[4] += v[4];
+    virial[5] += v[5];
+  }
+
+  if (vflag_atom) {
+    vatom[i][0] += v[0];
+    vatom[i][1] += v[1];
+    vatom[i][2] += v[2];
+    vatom[i][3] += v[3];
+    vatom[i][4] += v[4];
+    vatom[i][5] += v[5];
+  }
+}
+
+/* ----------------------------------------------------------------------
+   tally virial component into global and per-atom accumulators
+   n = index of virial component (0-5)
+   i = local index of atom
+   vn = nth component of virial for the interaction
+   increment nth component of global virial by vn
+   increment nth component of per-atom virial by vn
+   this method can be used when fix computes forces in post_force()
+   and the force depends on a distance to some external object
+     e.g. fix wall/lj93: compute virial only on owned atoms
+------------------------------------------------------------------------- */
+
+void Fix::v_tally(int n, int i, double vn)
+{
+
+  if (vflag_global)
+    virial[n] += vn;
+
+  if (vflag_atom)
+    vatom[i][n] += vn;
+}
diff --git a/src/fix.h b/src/fix.h
index d91937848a..3f32895309 100644
--- a/src/fix.h
+++ b/src/fix.h
@@ -36,6 +36,7 @@ class Fix : protected Pointers {
 
   bigint next_reneighbor;        // next timestep to force a reneighboring
   int thermo_energy;             // 1 if fix_modify enabled ThEng, 0 if not
+  int thermo_virial;             // 1 if fix_modify enabled ThVir, 0 if not
   int nevery;                    // how often to call an end_of_step fix
   int rigid_flag;                // 1 if Fix integrates rigid bodies, 0 if not
   int peatom_flag;               // 1 if Fix contributes per-atom eng, 0 if not
@@ -223,6 +224,8 @@ class Fix : protected Pointers {
   void ev_tally(int, int *, double, double, double *);
   void v_setup(int);
   void v_tally(int, int *, double, double *);
+  void v_tally(int, double *);
+  void v_tally(int, int, double);
 
   // union data struct for packing 32-bit and 64-bit ints into double bufs
   // see atom_vec.h for documentation