diff --git a/src/kspace.cpp b/src/kspace.cpp
index 216e74474a..8f25b718f2 100644
--- a/src/kspace.cpp
+++ b/src/kspace.cpp
@@ -15,6 +15,7 @@
 #include "string.h"
 #include "kspace.h"
 #include "error.h"
+#include "comm.h"
 
 using namespace LAMMPS_NS;
 
@@ -60,7 +61,9 @@ void KSpace::modify_params(int narg, char **arg)
       if (iarg+2 > narg) error->all("Illegal kspace_modify command");
       slab_volfactor = atof(arg[iarg+1]);
       iarg += 2;
-      if (slab_volfactor < 2.0) error->all("Bad slab parameter");
+      if (slab_volfactor <= 1.0) error->all("Bad slab parameter");
+      if (slab_volfactor < 2.0 && comm->me == 0) 
+	error->warning("Slab parameter < 2.0 may cause unphysical behavior");
       slabflag = 1;
     } else error->all("Illegal kspace_modify command");
   }