diff --git a/tests/core/Test_where_extended.cc b/tests/core/Test_where_extended.cc
new file mode 100644
index 00000000..706fd7ee
--- /dev/null
+++ b/tests/core/Test_where_extended.cc
@@ -0,0 +1,137 @@
+    /*************************************************************************************
+
+    Grid physics library, www.github.com/paboyle/Grid 
+
+    Source file: ./tests/Test_poisson_fft.cc
+
+    Copyright (C) 2015
+
+Author: Azusa Yamaguchi <ayamaguc@staffmail.ed.ac.uk>
+Author: Peter Boyle <paboyle@ph.ed.ac.uk>
+
+    This program is free software; you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation; either version 2 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License along
+    with this program; if not, write to the Free Software Foundation, Inc.,
+    51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+
+    See the full license in the file "LICENSE" in the top level distribution directory
+    *************************************************************************************/
+    /*  END LEGAL */
+#include <Grid/Grid.h>
+
+using namespace Grid;
+ ;
+
+int main (int argc, char ** argv)
+{
+  Grid_init(&argc,&argv);
+
+  int threads = GridThread::GetThreads();
+  std::cout<<GridLogMessage << "Grid is setup to use "<<threads<<" threads"<<std::endl;
+
+  int N=16;
+  
+  std::vector<int> latt_size  ({N,4,4});
+  std::vector<int> simd_layout({vComplexD::Nsimd(),1,1});
+  std::vector<int> mpi_layout ({1,1,1});
+
+  int vol = 1;
+  int nd  = latt_size.size();
+  for(int d=0;d<nd;d++){
+    vol = vol * latt_size[d];
+  }
+
+  GridCartesian         GRID(latt_size,simd_layout,mpi_layout);
+
+  LatticeComplexD      zz(&GRID);
+  LatticeInteger     coor(&GRID);
+  LatticeComplexD  rn(&GRID);
+  LatticeComplexD  sl(&GRID);
+
+  zz  = ComplexD(0.0,0.0);
+
+  GridParallelRNG RNG(&GRID);
+  RNG.SeedFixedIntegers(std::vector<int>({45,12,81,9}));  
+  gaussian(RNG,rn);
+
+  RealD nn=norm2(rn);
+  for(int mu=0;mu<nd;mu++){
+    RealD ns=0.0;
+    for(int t=0;t<latt_size[mu];t++){
+      LatticeCoordinate(coor,mu);
+      sl=where(coor==Integer(t),rn,zz);
+      std::cout <<GridLogMessage<< " sl " << sl<<std::endl;
+      std::cout <<GridLogMessage<<" slice "<<t<<" " << norm2(sl)<<std::endl;
+      ns=ns+norm2(sl);
+    }
+    std::cout <<GridLogMessage <<" sliceNorm" <<mu<<" "<< nn <<" "<<ns<<" " << nn-ns<<std::endl;
+  }
+
+  unsigned int tmin = 3;
+
+  int Ls = 2;
+  GridCartesian * UGrid   = SpaceTimeGrid::makeFourDimGrid(GridDefaultLatt(), GridDefaultSimd(Nd,vComplex::Nsimd()),GridDefaultMpi());
+  GridCartesian * FGrid   = SpaceTimeGrid::makeFiveDimGrid(Ls,UGrid);
+  std::vector<int> seeds4({1,2,3,4});
+  GridParallelRNG  RNG4(UGrid);  RNG4.SeedFixedIntegers(seeds4);
+  LatticeInteger lcoor(UGrid); LatticeCoordinate(lcoor,Nd-1);
+
+
+  std::cout<<GridLogMessage<<"=============================================================="<<std::endl;
+  std::cout<<GridLogMessage<<"== LatticeFermion =="<<std::endl;
+  std::cout<<GridLogMessage<<"=============================================================="<<std::endl;
+
+  LatticeFermion  q_outF(FGrid); q_outF=0.0;
+  LatticeFermion  tmpF(UGrid); random(RNG4,tmpF);
+  LatticeFermion  tmp2F(UGrid);
+  LatticeFermion  ZZF (UGrid);   ZZF=0.0;
+
+  RealD nA=0.0;
+  RealD nB=0.0;
+  for(int s=0;s<Ls;s++){
+    nB = nB + norm2(tmpF); 
+    tmp2F   = where((lcoor>=tmin),tmpF,ZZF);
+    nA = nA + norm2(tmp2F); 
+    InsertSlice(tmp2F, q_outF, s , 0);
+  }
+
+  RealD nQO=norm2(q_outF);
+  std::cout <<GridLogMessage << "norm_before_where: " << nB << std::endl;
+  std::cout <<GridLogMessage << "norm_after_where: " << nA << std::endl;
+  std::cout <<GridLogMessage << "norm_q_out: " << nQO << std::endl;
+
+
+  std::cout<<GridLogMessage<<"=============================================================="<<std::endl;
+  std::cout<<GridLogMessage<<"== LatticePropagator =="<<std::endl;
+  std::cout<<GridLogMessage<<"=============================================================="<<std::endl;
+
+  LatticePropagator  q_outP(FGrid); q_outP=0.0;
+  LatticePropagator  tmpP(UGrid); random(RNG4,tmpP);
+  LatticePropagator  tmp2P(UGrid);
+  LatticePropagator  ZZP (UGrid);   ZZP=0.0;
+
+  nA=0.0;
+  nB=0.0;
+  for(int s=0;s<Ls;s++){
+    nB = nB + norm2(tmpP); 
+    tmp2P   = where((lcoor>=tmin),tmpP,ZZP);
+    nA = nA + norm2(tmp2P); 
+    InsertSlice(tmp2P, q_outP, s , 0);
+  }
+
+  nQO=norm2(q_outP);
+  std::cout <<GridLogMessage << "norm_before_where: " << nB << std::endl;
+  std::cout <<GridLogMessage << "norm_after_where: " << nA << std::endl;
+  std::cout <<GridLogMessage << "norm_q_out: " << nQO << std::endl;
+
+  Grid_finalize();
+}