diff --git a/Grid/algorithms/iterative/ConjugateGradientMultiShift.h b/Grid/algorithms/iterative/ConjugateGradientMultiShift.h
index 252e4506..3b079e99 100644
--- a/Grid/algorithms/iterative/ConjugateGradientMultiShift.h
+++ b/Grid/algorithms/iterative/ConjugateGradientMultiShift.h
@@ -182,6 +182,9 @@ public:
     for(int s=0;s<nshift;s++) {
       axpby(psi[s],0.,-bs[s]*alpha[s],src,src);
     }
+
+    std::cout << GridLogIterative << "ConjugateGradientMultiShift: initial rn (|src|^2) =" << rn << " qq (|MdagM src|^2) =" << qq << " d ( dot(src, [MdagM + m_0]src) ) =" << d << " c=" << c << std::endl;
+    
   
   ///////////////////////////////////////
   // Timers
diff --git a/Grid/lattice/Lattice.h b/Grid/lattice/Lattice.h
index 9f5f1da7..c4adf86a 100644
--- a/Grid/lattice/Lattice.h
+++ b/Grid/lattice/Lattice.h
@@ -46,3 +46,4 @@ Author: Peter Boyle <paboyle@ph.ed.ac.uk>
 #include <Grid/lattice/Lattice_unary.h>
 #include <Grid/lattice/Lattice_transfer.h>
 #include <Grid/lattice/Lattice_basis.h>
+#include <Grid/lattice/Lattice_crc.h>
diff --git a/Grid/lattice/Lattice_crc.h b/Grid/lattice/Lattice_crc.h
new file mode 100644
index 00000000..a283ea8b
--- /dev/null
+++ b/Grid/lattice/Lattice_crc.h
@@ -0,0 +1,42 @@
+/*************************************************************************************
+
+    Grid physics library, www.github.com/paboyle/Grid 
+
+    Source file: ./lib/lattice/Lattice_crc.h
+
+    Copyright (C) 2021
+
+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 */
+#pragma once
+
+NAMESPACE_BEGIN(Grid);
+
+template<class vobj> uint32_t crc(Lattice<vobj> & buf)
+{
+  autoView( buf_v , buf, CpuRead);
+  return ::crc32(0L,(unsigned char *)&buf_v[0],(size_t)sizeof(vobj)*buf.oSites());
+}
+
+#define CRC(U) std::cout << "FingerPrint "<<__FILE__ <<" "<< __LINE__ <<" "<< #U <<" "<<crc(U)<<std::endl;
+
+NAMESPACE_END(Grid);
+
+
diff --git a/HMC/DWF2p1fIwasakiGparity.cc b/HMC/DWF2p1fIwasakiGparity.cc
index e9865a54..c02ada51 100644
--- a/HMC/DWF2p1fIwasakiGparity.cc
+++ b/HMC/DWF2p1fIwasakiGparity.cc
@@ -354,7 +354,7 @@ int main(int argc, char **argv) {
  
   //Setup the BCs
   FermionActionD::ImplParams Params;
-  for(int i=0;i<Nd-1;i++) Params.twists = user_params.GparityDirs[i]; //G-parity directions
+  for(int i=0;i<Nd-1;i++) Params.twists[i] = user_params.GparityDirs[i]; //G-parity directions
   Params.twists[Nd-1] = 1; //APBC in time direction
 
   std::vector<int> dirs4(Nd);
diff --git a/HMC/DWF2p1fIwasakiGparityRHMCdouble.cc b/HMC/DWF2p1fIwasakiGparityRHMCdouble.cc
index 533ad8a2..58295d5e 100644
--- a/HMC/DWF2p1fIwasakiGparityRHMCdouble.cc
+++ b/HMC/DWF2p1fIwasakiGparityRHMCdouble.cc
@@ -354,7 +354,7 @@ int main(int argc, char **argv) {
  
   //Setup the BCs
   FermionActionD::ImplParams Params;
-  for(int i=0;i<Nd-1;i++) Params.twists = user_params.GparityDirs[i]; //G-parity directions
+  for(int i=0;i<Nd-1;i++) Params.twists[i] = user_params.GparityDirs[i]; //G-parity directions
   Params.twists[Nd-1] = 1; //APBC in time direction
 
   std::vector<int> dirs4(Nd);