diff --git a/src/fix_nh.cpp b/src/fix_nh.cpp
index 0f1f3395dd51d8a5bcddb7fe3ccbcb63c454f055..c99c7a34bdf66ce9a40041689a8a9f30a5686518 100644
--- a/src/fix_nh.cpp
+++ b/src/fix_nh.cpp
@@ -133,7 +133,7 @@ FixNH::FixNH(LAMMPS *lmp, int narg, char **arg) :
       t_target = t_start;
       t_stop = force->numeric(FLERR,arg[iarg+2]);
       t_period = force->numeric(FLERR,arg[iarg+3]);
-      if (t_start < 0.0 || t_stop <= 0.0)
+      if (t_start <= 0.0 || t_stop <= 0.0)
         error->all(FLERR,
                    "Target temperature for fix nvt/npt/nph cannot be 0.0");
       iarg += 4;