diff --git a/src/fix_wall_reflect.cpp b/src/fix_wall_reflect.cpp
index f21e98ac2e..7e93c2da0e 100644
--- a/src/fix_wall_reflect.cpp
+++ b/src/fix_wall_reflect.cpp
@@ -11,16 +11,22 @@
    See the README file in the top-level LAMMPS directory.
 ------------------------------------------------------------------------- */
 
+#include "stdlib.h"
 #include "string.h"
 #include "fix_wall_reflect.h"
 #include "atom.h"
 #include "comm.h"
 #include "modify.h"
 #include "domain.h"
+#include "lattice.h"
+#include "input.h"
+#include "variable.h"
 #include "error.h"
 
 using namespace LAMMPS_NS;
 
+enum{NONE,EDGE,CONSTANT,VARIABLE};
+
 /* ---------------------------------------------------------------------- */
 
 FixWallReflect::FixWallReflect(LAMMPS *lmp, int narg, char **arg) :
@@ -28,17 +34,143 @@ FixWallReflect::FixWallReflect(LAMMPS *lmp, int narg, char **arg) :
 {
   if (narg < 4) error->all("Illegal fix wall/reflect command");
 
-  xloflag = xhiflag = yloflag = yhiflag = zloflag = zhiflag = 0;
-  for (int iarg = 3; iarg < narg; iarg++) {
-    if (strcmp(arg[iarg],"xlo") == 0) xloflag = 1;
-    else if (strcmp(arg[iarg],"xhi") == 0) xhiflag = 1;
-    else if (strcmp(arg[iarg],"ylo") == 0) yloflag = 1;
-    else if (strcmp(arg[iarg],"yhi") == 0) yhiflag = 1;
-    else if (strcmp(arg[iarg],"zlo") == 0) zloflag = 1;
-    else if (strcmp(arg[iarg],"zhi") == 0) zhiflag = 1;
-    else error->all("Illegal fix wall/reflect command");
+  xloflag = xhiflag = yloflag = yhiflag = zloflag = zhiflag = NONE;
+  xlostr = xhistr = ylostr = yhistr = zlostr = zhistr = NULL;
+  int scaleflag = 1;
+
+  int iarg = 3;
+  while (iarg < narg) {
+    if (strcmp(arg[iarg],"xlo") == 0) {
+      if (iarg+2 > narg) error->all("Illegal fix wall/reflect command");
+      if (strcmp(arg[iarg+1],"EDGE") == 0) {
+	xloflag = EDGE;
+	xlo = domain->boxlo[0];
+      } else if (strstr(arg[iarg+1],"v_") == arg[iarg+1]) {
+	xloflag = VARIABLE;
+	int n = strlen(&arg[iarg+1][2]) + 1;
+	xlostr = new char[n];
+	strcpy(xlostr,&arg[iarg+1][2]);
+      } else {
+	xloflag = CONSTANT;
+	xlo = atof(arg[iarg+1]);
+      }
+      iarg += 2;
+    } else if (strcmp(arg[iarg],"xhi") == 0) {
+      if (iarg+2 > narg) error->all("Illegal fix wall/reflect command");
+      if (strcmp(arg[iarg+1],"EDGE") == 0) {
+	xhiflag = EDGE;
+	xhi = domain->boxhi[0];
+      } else if (strstr(arg[iarg+1],"v_") == arg[iarg+1]) {
+	xhiflag = VARIABLE;
+	int n = strlen(&arg[iarg+1][2]) + 1;
+	xhistr = new char[n];
+	strcpy(xhistr,&arg[iarg+1][2]);
+      } else {
+	xhiflag = CONSTANT;
+	xhi = atof(arg[iarg+1]);
+      }
+      iarg += 2;
+    } else if (strcmp(arg[iarg],"ylo") == 0) {
+      if (iarg+2 > narg) error->all("Illegal fix wall/reflect command");
+      if (strcmp(arg[iarg+1],"EDGE") == 0) {
+	yloflag = EDGE;
+	ylo = domain->boxlo[0];
+      } else if (strstr(arg[iarg+1],"v_") == arg[iarg+1]) {
+	yloflag = VARIABLE;
+	int n = strlen(&arg[iarg+1][2]) + 1;
+	ylostr = new char[n];
+	strcpy(ylostr,&arg[iarg+1][2]);
+      } else {
+	yloflag = CONSTANT;
+	ylo = atof(arg[iarg+1]);
+      }
+      iarg += 2;
+    } else if (strcmp(arg[iarg],"yhi") == 0) {
+      if (iarg+2 > narg) error->all("Illegal fix wall/reflect command");
+      if (strcmp(arg[iarg+1],"EDGE") == 0) {
+	yhiflag = EDGE;
+	yhi = domain->boxhi[0];
+      } else if (strstr(arg[iarg+1],"v_") == arg[iarg+1]) {
+	yhiflag = VARIABLE;
+	int n = strlen(&arg[iarg+1][2]) + 1;
+	yhistr = new char[n];
+	strcpy(yhistr,&arg[iarg+1][2]);
+      } else {
+	yhiflag = CONSTANT;
+	yhi = atof(arg[iarg+1]);
+      }
+      iarg += 2;
+    } else if (strcmp(arg[iarg],"zlo") == 0) {
+      if (iarg+2 > narg) error->all("Illegal fix wall/reflect command");
+      if (strcmp(arg[iarg+1],"EDGE") == 0) {
+	zloflag = EDGE;
+	zlo = domain->boxlo[0];
+      } else if (strstr(arg[iarg+1],"v_") == arg[iarg+1]) {
+	zloflag = VARIABLE;
+	int n = strlen(&arg[iarg+1][2]) + 1;
+	zlostr = new char[n];
+	strcpy(zlostr,&arg[iarg+1][2]);
+      } else {
+	zloflag = CONSTANT;
+	zlo = atof(arg[iarg+1]);
+      }
+      iarg += 2;
+    } else if (strcmp(arg[iarg],"zhi") == 0) {
+      if (iarg+2 > narg) error->all("Illegal fix wall/reflect command");
+      if (strcmp(arg[iarg+1],"EDGE") == 0) {
+	zhiflag = EDGE;
+	zhi = domain->boxhi[0];
+      } else if (strstr(arg[iarg+1],"v_") == arg[iarg+1]) {
+	zhiflag = VARIABLE;
+	int n = strlen(&arg[iarg+1][2]) + 1;
+	zhistr = new char[n];
+	strcpy(zhistr,&arg[iarg+1][2]);
+      } else {
+	zhiflag = CONSTANT;
+	zhi = atof(arg[iarg+1]);
+      }
+      iarg += 2;
+
+    } else if (strcmp(arg[iarg],"units") == 0) {
+      if (iarg+2 > narg) error->all("Illegal wall/reflect command");
+      if (strcmp(arg[iarg+1],"box") == 0) scaleflag = 0;
+      else if (strcmp(arg[iarg+1],"lattice") == 0) scaleflag = 1;
+      else error->all("Illegal fix wall/reflect command");
+      iarg += 2;
+    } else error->all("Illegal fix wall/reflect command");
   }
 
+  // setup scaling if any wall positions were set as CONSTANT
+  // apply scaling factors to wall positions
+
+  if (xloflag == CONSTANT || xhiflag == CONSTANT ||
+      yloflag == CONSTANT || yhiflag == CONSTANT ||
+      zloflag == CONSTANT || zhiflag == CONSTANT) {
+
+    if (scaleflag && domain->lattice == NULL)
+      error->all("Use of fix wall/reflect with undefined lattice");
+
+    double xscale,yscale,zscale;
+    if (scaleflag) {
+      xscale = domain->lattice->xlattice;
+      yscale = domain->lattice->ylattice;
+      zscale = domain->lattice->zlattice;
+    }
+    else xscale = yscale = zscale = 1.0;
+
+    if (xloflag == CONSTANT) xlo *= xscale;
+    if (xhiflag == CONSTANT) xhi *= xscale;
+    if (yloflag == CONSTANT) ylo *= xscale;
+    if (yhiflag == CONSTANT) yhi *= xscale;
+    if (zloflag == CONSTANT) zlo *= xscale;
+    if (zhiflag == CONSTANT) zhi *= xscale;
+  }
+
+  // error checks
+
+  if (!xloflag && !xhiflag && !yloflag && !yhiflag && !zloflag && !zhiflag)
+    error->all("Illegal fix wall/reflect command");
+
   if ((xloflag || xhiflag) && domain->xperiodic)
     error->all("Cannot use wall in periodic dimension");
   if ((yloflag || yhiflag) && domain->yperiodic)
@@ -49,6 +181,18 @@ FixWallReflect::FixWallReflect(LAMMPS *lmp, int narg, char **arg) :
 
 /* ---------------------------------------------------------------------- */
 
+FixWallReflect::~FixWallReflect()
+{
+  delete [] xlostr;
+  delete [] xhistr;
+  delete [] ylostr;
+  delete [] yhistr;
+  delete [] zlostr;
+  delete [] zhistr;
+}
+
+/* ---------------------------------------------------------------------- */
+
 int FixWallReflect::setmask()
 {
   int mask = 0;
@@ -61,6 +205,49 @@ int FixWallReflect::setmask()
 
 void FixWallReflect::init()
 {
+  if (xlostr) {
+    xlovar = input->variable->find(xlostr);
+    if (xlovar < 0)
+      error->all("Variable name for fix wall/relect does not exist");
+    if (!input->variable->equalstyle(xlovar))
+      error->all("Variable for fix wall/reflect is not equal style");
+  }
+  if (xhistr) {
+    xhivar = input->variable->find(xhistr);
+    if (xhivar < 0)
+      error->all("Variable name for fix wall/relect does not exist");
+    if (!input->variable->equalstyle(xhivar))
+      error->all("Variable for fix wall/reflect is not equal style");
+  }
+  if (ylostr) {
+    ylovar = input->variable->find(ylostr);
+    if (ylovar < 0)
+      error->all("Variable name for fix wall/relect does not exist");
+    if (!input->variable->equalstyle(ylovar))
+      error->all("Variable for fix wall/reflect is not equal style");
+  }
+  if (yhistr) {
+    yhivar = input->variable->find(yhistr);
+    if (yhivar < 0)
+      error->all("Variable name for fix wall/relect does not exist");
+    if (!input->variable->equalstyle(yhivar))
+      error->all("Variable for fix wall/reflect is not equal style");
+  }
+  if (zlostr) {
+    zlovar = input->variable->find(zlostr);
+    if (zlovar < 0)
+      error->all("Variable name for fix wall/relect does not exist");
+    if (!input->variable->equalstyle(zlovar))
+      error->all("Variable for fix wall/reflect is not equal style");
+  }
+  if (zhistr) {
+    zhivar = input->variable->find(zhistr);
+    if (zhivar < 0)
+      error->all("Variable name for fix wall/relect does not exist");
+    if (!input->variable->equalstyle(zhivar))
+      error->all("Variable for fix wall/reflect is not equal style");
+  }
+
   int nrigid = 0;
   for (int i = 0; i < modify->nfix; i++)
     if (modify->fix[i]->rigid_flag) nrigid++;
@@ -74,12 +261,12 @@ void FixWallReflect::init()
 
 void FixWallReflect::post_integrate()
 {
-  double xlo = domain->boxlo[0];
-  double xhi = domain->boxhi[0];
-  double ylo = domain->boxlo[1];
-  double yhi = domain->boxhi[1];
-  double zlo = domain->boxlo[2];
-  double zhi = domain->boxhi[2];
+  if (xloflag == VARIABLE) xlo = input->variable->compute_equal(xlovar);
+  if (xhiflag == VARIABLE) xhi = input->variable->compute_equal(xhivar);
+  if (yloflag == VARIABLE) ylo = input->variable->compute_equal(ylovar);
+  if (yhiflag == VARIABLE) yhi = input->variable->compute_equal(yhivar);
+  if (zloflag == VARIABLE) zlo = input->variable->compute_equal(zlovar);
+  if (zhiflag == VARIABLE) zhi = input->variable->compute_equal(zhivar);
 
   double **x = atom->x;
   double **v = atom->v;
diff --git a/src/fix_wall_reflect.h b/src/fix_wall_reflect.h
index 6d0c3cb47d..f0f7ef41fb 100644
--- a/src/fix_wall_reflect.h
+++ b/src/fix_wall_reflect.h
@@ -27,12 +27,16 @@ namespace LAMMPS_NS {
 class FixWallReflect : public Fix {
  public:
   FixWallReflect(class LAMMPS *, int, char **);
+  ~FixWallReflect();
   int setmask();
   void init();
   void post_integrate();
 
  private:
   int xloflag,xhiflag,yloflag,yhiflag,zloflag,zhiflag;
+  char *xlostr,*xhistr,*ylostr,*yhistr,*zlostr,*zhistr;
+  int xlovar,xhivar,ylovar,yhivar,zlovar,zhivar;
+  double xlo,xhi,ylo,yhi,zlo,zhi;
 };
 
 }