diff --git a/sapporo2/get_sapporo.sh b/sapporo2/get_sapporo.sh
index 1a45a67..f5eea23 100755
--- a/sapporo2/get_sapporo.sh
+++ b/sapporo2/get_sapporo.sh
@@ -3,7 +3,29 @@ commit=7c3f80acf1df5a8907118706a2260184cfccc6a1
 archive_md5sum=b7b17eeded2cb5dfb9e174424b3f7ecb
 url=https://github.com/treecode/sapporo2/archive/$commit.tar.gz
 wget -O sapporo2.tar.gz $url
+
+# Verify source.
 md5sum --check <<<"$archive_md5sum sapporo2.tar.gz"
+
+# Protect .gitignore.
+cp -rp .gitignore .gitignore~
+
+# Untar original source.
 tar --strip-components=1 -xvf sapporo2.tar.gz
-rm -f sapporo2.tar.gz
+
+# Restore .gitignore
+mv .gitignore~ .gitignore
+
+# Cleanup unused bits
+rm -rf sapporo2.tar.gz                  \
+       lib/include/vec.h                \
+       lib/include/ocldev.h*            \
+       lib/include/SSE_AVX              \
+       lib/interfaces/sapporo6thlib.cpp \
+       lib/interfaces/sapporoG5lib.cpp  \
+       lib/interfaces/sapporoYeblib.cpp \
+       lib/Makefile_ocl                 \
+       lib/OpenCLKernels
+
+# Patch source.
 patch -p0 < patch.diff
diff --git a/sapporo2/patch.diff b/sapporo2/patch.diff
index 89a0747..1b565be 100644
--- a/sapporo2/patch.diff
+++ b/sapporo2/patch.diff
@@ -1,5 +1,5 @@
 --- lib/CUDAKernels/kernels.cu
-+++
++++ lib/CUDAKernels/kernels.cu
 @@ -206,7 +206,7 @@
  // template<>           __device__ __forceinline__  double RSQRT(double val) { return 1.0/sqrt(val); }
  
@@ -19,7 +19,7 @@
  __device__ __forceinline__ double atomicMin(double *address, double val)
  {
 --- lib/include/sapdevclass.h
-+++
++++ lib/include/sapdevclass.h
 @@ -33,7 +33,10 @@
  
  #include <cassert>
@@ -33,8 +33,46 @@
  #include <sys/time.h>
  
 --- lib/interfaces/sapporoG6lib.cpp
-+++
-@@ -45,34 +45,9 @@
++++ lib/interfaces/sapporoG6lib.cpp
+@@ -1,3 +1,5 @@
++#include <cstdlib>
++#include <fstream>
+ #include "sapporohostclass.h"
+ 
+ sapporo grav;
+@@ -10,11 +12,6 @@
+ 
+ extern "C" {
+ 
+-#ifdef _OCL_ 
+-  const char *kernelFile = "OpenCL/kernels4th.cl";    
+-#else
+-  const char *kernelFile = "CUDA/kernels.ptx";	
+-#endif  
+   double *dsmin_i;        //Distance of nearest neighbour
+   
+   double acc_i[3];      //To store the multiplied acc
+@@ -29,6 +26,19 @@
+     //devices to use. Otherwise they should be specified in the config file
+ 
+     //Open the GPUs
++
++    char kernelFile[1024];
++    if (const char* kernelFile_env = std::getenv("SAPPORO2_KERNEL_FILE"))
++      strncpy(kernelFile, kernelFile_env, 1024);
++    else
++      strcpy(kernelFile, "CUDA/kernels.ptx");
++    
++    std::ifstream file(kernelFile);
++    if (!file.is_open()) {
++      std::cout << "Kernel file " << kernelFile << " not found! Please set the SAPPORO2_KERNEL_FILE environment variable.";
++      exit(1);
++    }
++    
+     
+     //Double single, default
+     int res     = grav.open(kernelFile, list, ndev, FOURTH, DOUBLESINGLE);
+@@ -45,34 +55,9 @@
    
    int g6_open_(int *id)
    {
@@ -73,39 +111,46 @@
    }
  
 --- lib/Makefile
-+++
-@@ -1,11 +1,13 @@
++++ lib/Makefile
+@@ -1,84 +1,27 @@
 -CXX = g++
 -CC  = gcc
 -LD  = g++ 
 -F90  = ifort
-+CXX ?= g++
-+CC  ?= gcc
-+LD  ?= g++ 
-+F90 ?= ifort
- 
- .SUFFIXES: .o .cpp .ptx .cu
- 
+-
+-.SUFFIXES: .o .cpp .ptx .cu
+-
 -CUDA_TK  ?= /usr/local/cuda
-+CUDA_HOME ?= /usr/local/cuda
-+CUDA_TK    = $(CUDA_HOME)
-+OPTIMIZATION ?= 3
- 
- 
- testRunFlags1=
-@@ -24,7 +26,7 @@
- 	testRunFlags3="-D TIMING_STATS=1"
- endif
- 
+-
+-
+-testRunFlags1=
+-testRunFlags2=
+-testRunFlags3=
+-
+-#Check for the defines 
+-
+-ifdef NTHREADS
+-	testRunFlags1="-D NTHREADS=$(NTHREADS)"
+-	testRunFlags3="-D TIMING_STATS=1"
+-endif
+-
+-ifdef NBLOCKS_PER_MULTI
+-	testRunFlags2="-D NBLOCKS_PER_MULTI=$(NBLOCKS_PER_MULTI)"
+-	testRunFlags3="-D TIMING_STATS=1"
+-endif
+-
 -OFLAGS = -g -O3 -Wall -Wextra -Wstrict-aliasing=2 -fopenmp
-+OFLAGS = -g -O$(OPTIMIZATION) -Wall -Wextra -Wstrict-aliasing=2
- 
- #Use below if compiling with CPU_SUPPORT (SSE)
- #CXXFLAGS += ${testRunFlags} -fPIC $(OFLAGS) -I$(CUDA_TK)/include -msse4
-@@ -36,23 +38,14 @@
- NVCC      = $(CUDA_TK)/bin/nvcc
- 
- 
+-
+-#Use below if compiling with CPU_SUPPORT (SSE)
+-#CXXFLAGS += ${testRunFlags} -fPIC $(OFLAGS) -I$(CUDA_TK)/include -msse4
+-CXXFLAGS += ${testRunFlags} -fPIC $(OFLAGS) -I$(CUDA_TK)/include
+-
+-testRunFlags= $(testRunFlags1) $(testRunFlags2) $(testRunFlags3)
+-$(info $(testRunFlags))
+-
+-NVCC      = $(CUDA_TK)/bin/nvcc
+-
+-
 -# Support older CUDA versions out of the box
 -NVCCVERSION=$(shell "${NVCC}" --version | grep ^Cuda | sed 's/^.* //g')
 -ifeq "${NVCCVERSION}" "V5.5.22"
@@ -117,15 +162,67 @@
 -#NVCCFLAGS = -arch sm_35
 -#NVCCFLAGS ?= -arch sm_30
 -#NVCCFLAGS = -arch sm_20
-+GPUARCH   ?= sm_75
-+NVCCFLAGS  = -arch $(GPUARCH) -ccbin $(CXX)
- NVCCFLAGS +=  ${testRunFlags}
- 
- # Use with Mac OS X
- # NVCCFLAGS = -arch sm_12 -Xcompiler="-Duint=unsigned\ int"
- 
+-NVCCFLAGS +=  ${testRunFlags}
+-
+-# Use with Mac OS X
+-# NVCCFLAGS = -arch sm_12 -Xcompiler="-Duint=unsigned\ int"
+-
 -LDFLAGS = -lcuda -fopenmp 
-+LDFLAGS = -lcuda
- 
- 
+-
+-
++NVCC     = nvcc
++GPUARCH ?= sm_75
++OPTIMIZATION ?= 3
++
++CUDA_HOME ?= /usr/local/cuda
++OFLAGS = -g -O$(OPTIMIZATION) -Wall -Wextra -Wstrict-aliasing=2
++CXXFLAGS += -fPIC $(OFLAGS) -I$(CUDA_HOME)/include
++NVCCFLAGS  = -arch $(GPUARCH) -ccbin $(CXX)
  INCLUDEPATH = ./include
+ CXXFLAGS  += -I$(INCLUDEPATH) -I./
+ NVCCFLAGS += -I$(INCLUDEPATH) -I./
+-
+ INTERFACEPATH =./interfaces
+-
+ CUDAKERNELSPATH = ./CUDAKernels
+ CUDAKERNELS = kernels.cu
+-
+ CUDAPTX = $(CUDAKERNELS:%.cu=$(CUDAKERNELSPATH)/%.ptx)
+-
+ SRCPATH = src
+-SRC = sapporohostclass.cpp sapporoG6lib.cpp sapporoYeblib.cpp sapporoG5lib.cpp sapporo6thlib.cpp
++SRC = sapporohostclass.cpp sapporoG6lib.cpp
+ OBJ = $(SRC:%.cpp=%.o)
+-
+-LIBOBJ = sapporohostclass.o $(INTERFACEPATH)/sapporoG6lib.o $(INTERFACEPATH)/sapporoYeblib.o
+-LIBOBJ += $(INTERFACEPATH)/sapporoG5lib.o
++LIBOBJ = sapporohostclass.o $(INTERFACEPATH)/sapporoG6lib.o
+ TARGET = libsapporo.a
+ 
+-
+ all:	  $(OBJ) $(CUDAPTX) $(TARGET)
+ kernels:  $(CUDAPTX)
+ 
+-
+ $(TARGET): $(LIBOBJ)
+ 	ar qv $@ $^        
+ 
+@@ -99,16 +42,9 @@
+ 
+ $(OBJ): $(INCLUDEPATH)/*.h
+ 
+-
+ sapporohostclass.o : $(INCLUDEPATH)/kernels.ptxh $(INCLUDEPATH)/sapporohostclass.h $(INCLUDEPATH)/sapdevclass.h $(INCLUDEPATH)/defines.h
+ $(CUDAKERNELSPATH)/kernels.ptx : $(INCLUDEPATH)/defines.h
+ 
+ libsapporo.a : sapporohostclass.o
+ 
+-
+-
+-
+-
+-
+-
+-
++.SUFFIXES: .o .cpp .ptx .cu
+\ No newline at end of file
\ No newline at end of file