diff --git a/Makefile b/Makefile
index 4bf9dad..6b25288 100644
--- a/Makefile
+++ b/Makefile
@@ -22,9 +22,9 @@ sa-solver : ${OBJ}
 ${OBJ} : ${INCLUDES}
 
 _kernel.h : input.cl param.h
-	echo 'const char *ocl_code = R"_mrb_(' >$@
-	cpp $< >>$@
-	echo ')_mrb_";' >>$@
+	cpp $< ocl.code
+	printf "\x00" >> ocl.code
+	xxd -i ocl.code $@
 
 test : sa-solver
 	@echo Testing...
@@ -38,6 +38,6 @@ test : sa-solver
 #	different: testing/sols-100
 
 clean :
-	rm -f sa-solver _kernel.h *.o _temp_*
+	rm -f sa-solver _kernel.h *.o _temp_* ocl.code
 
 re : clean all
diff --git a/main.c b/main.c
index 9ebc242..2144792 100644
--- a/main.c
+++ b/main.c
@@ -1277,8 +1277,8 @@ void init_and_run_opencl(uint8_t *header, size_t header_len)
     cl_program program;
     const char *source;
     size_t source_len;
-    source = ocl_code;
-    source_len = strlen(ocl_code);
+    source = (char *)ocl_code;
+    source_len = ocl_code_len - 1;
     program = clCreateProgramWithSource(context, 1, (const char **)&source,
 	    &source_len, &status);
     if (status != CL_SUCCESS || !program)