diff --git a/src/fix_langevin.cpp b/src/fix_langevin.cpp
index cf3161e8a8..9e857339b4 100644
--- a/src/fix_langevin.cpp
+++ b/src/fix_langevin.cpp
@@ -146,7 +146,13 @@ FixLangevin::FixLangevin(LAMMPS *lmp, int narg, char **arg) :
   temperature = NULL;
 
   energy = 0.0;
+
+  // flangevin is unallocated until first call to setup()
+  // compute_scalar checks for this and returns 0.0 
+  // if flangevin_allocated is not set
+
   flangevin = NULL;
+  flangevin_allocated = 0;
   franprev = NULL;
   tforce = NULL;
   maxatom1 = maxatom2 = 0;
@@ -510,6 +516,7 @@ void FixLangevin::post_force_untemplated
       maxatom1 = atom->nmax;
       memory->create(flangevin,maxatom1,3,"langevin:flangevin");
     }
+    flangevin_allocated = 1;
   }
 
   if (Tp_BIAS) temperature->compute_scalar();
@@ -824,7 +831,7 @@ int FixLangevin::modify_param(int narg, char **arg)
 
 double FixLangevin::compute_scalar()
 {
-  if (!tallyflag) return 0.0;
+  if (!tallyflag || !flangevin_allocated) return 0.0;
 
   // capture the very first energy transfer to thermal reservoir
 
diff --git a/src/fix_langevin.h b/src/fix_langevin.h
index 1e084c9e98..863c0f554c 100644
--- a/src/fix_langevin.h
+++ b/src/fix_langevin.h
@@ -47,6 +47,7 @@ class FixLangevin : public Fix {
 
  protected:
   int gjfflag,oflag,tallyflag,zeroflag,tbiasflag;
+  int flangevin_allocated;
   double ascale;
   double t_start,t_stop,t_period,t_target;
   double *gfactor1,*gfactor2,*ratio;