diff --git a/src/fix_nh.cpp b/src/fix_nh.cpp
index 22f07cedd7..a97026e778 100644
--- a/src/fix_nh.cpp
+++ b/src/fix_nh.cpp
@@ -442,11 +442,12 @@ FixNH::FixNH(LAMMPS *lmp, int narg, char **arg) : Fix(lmp, narg, arg)
   else if (pcouple == XYZ || (dimension == 2 && pcouple == XY)) pstyle = ISO;
   else pstyle = ANISO;
 
-  // reneighboring only forced if flips can occur due to shape changes
+  // pre_exchange only required if flips can occur due to shape changes
 
-  if (flipflag && (p_flag[3] || p_flag[4] || p_flag[5])) force_reneighbor = 1;
+  pre_exchange_flag = 0;
+  if (flipflag && (p_flag[3] || p_flag[4] || p_flag[5])) pre_exchange_flag = 1;
   if (flipflag && (domain->yz != 0.0 || domain->xz != 0.0 || domain->xy != 0.0))
-    force_reneighbor = 1;
+    pre_exchange_flag = 1;
 
   // convert input periods to frequencies
 
@@ -515,7 +516,7 @@ FixNH::FixNH(LAMMPS *lmp, int narg, char **arg) : Fix(lmp, narg, arg)
   nrigid = 0;
   rfix = NULL;
 
-  if (force_reneighbor) irregular = new Irregular(lmp);
+  if (pre_exchange_flag) irregular = new Irregular(lmp);
   else irregular = NULL;
 
   // initialize vol0,t0 to zero to signal uninitialized
@@ -567,7 +568,7 @@ int FixNH::setmask()
   mask |= THERMO_ENERGY;
   mask |= INITIAL_INTEGRATE_RESPA;
   mask |= FINAL_INTEGRATE_RESPA;
-  if (force_reneighbor) mask |= PRE_EXCHANGE;
+  if (pre_exchange_flag) mask |= PRE_EXCHANGE;
   return mask;
 }
 
diff --git a/src/fix_nh.h b/src/fix_nh.h
index fb141bbb7a..80a71b8843 100644
--- a/src/fix_nh.h
+++ b/src/fix_nh.h
@@ -114,6 +114,8 @@ class FixNH : public Fix {
   int scalexy;                     // 1 if xy scaled with ly
   int flipflag;                    // 1 if box flips are invoked as needed
 
+  int pre_exchange_flag;           // set if pre_exchange needed for box flips
+
   double fixedpoint[3];            // location of dilation fixed-point
 
   void couple();