diff --git a/Makefile.am b/Makefile.am
index a843f1d..5788ca8 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -18,6 +18,7 @@ unit_tests_extra=
 perf_tests_extra=
 examples=
 other_tests=
+lsrc_x86_64=
 lsrc32=
 unit_tests32=
 perf_tests32=
@@ -37,6 +38,19 @@ LIBISAL_AGE=0
 lib_LTLIBRARIES = libisal.la
 pkginclude_HEADERS += $(sort ${extern_hdrs})
 libisal_la_SOURCES = ${lsrc}
+
+if CPU_X86_64
+libisal_la_SOURCES += ${lsrc_x86_64}
+endif
+
+if CPU_X86_32
+libisal_la_SOURCES += ${lsrc_x86_32}
+endif
+
+if CPU_UNDEFINED
+libisal_la_SOURCES += ${lsrc_base_aliases}
+endif
+
 nobase_include_HEADERS = isa-l.h
 libisal_la_LDFLAGS = $(AM_LDFLAGS) \
 	-version-info $(LIBISAL_CURRENT):$(LIBISAL_REVISION):$(LIBISAL_AGE)
diff --git a/configure.ac b/configure.ac
index 531320d..a4abbfe 100644
--- a/configure.ac
+++ b/configure.ac
@@ -22,6 +22,17 @@ AM_INIT_AUTOMAKE([
 ])
 AM_PROG_AS
 
+AC_CANONICAL_HOST
+CPU=""
+AS_CASE([$host_cpu],
+  [x86_64], [CPU="x86_64"],
+  [amd64], [CPU="x86_64"],
+  [i?86], [CPU="x86_32"],
+)
+AM_CONDITIONAL([CPU_X86_64], [test "$CPU" = "x86_64"])
+AM_CONDITIONAL([CPU_X86_32], [test "$CPU" = "x86_32"])
+AM_CONDITIONAL([CPU_UNDEFINED], [test "x$CPU" = "x"])
+
 # Check for programs
 AC_PROG_CC_STDC
 AC_USE_SYSTEM_EXTENSIONS
@@ -114,7 +125,7 @@ AM_CONDITIONAL(USE_NASM, test x"$AS" = x"nasm")
 AM_CONDITIONAL(WITH_AVX512, test x"$have_as_knows_avx512" = x"yes")
 
 
-case $target in
+case $host_os in
      *linux*)	arch=linux   yasm_args="-f elf64";;
      *darwin*)	arch=darwin  yasm_args="-f macho64 --prefix=_ ";;
      *netbsd*)	arch=netbsd  yasm_args="-f elf64";;
diff --git a/make.inc b/make.inc
index d1689cd..0f791a3 100644
--- a/make.inc
+++ b/make.inc
@@ -40,6 +40,8 @@
 #	clean - remove object files
 
 version ?= 2.17.0
+host_cpu ?= $(shell uname -m | sed -e 's/amd/x86_/')
+arch ?= $(shell uname | grep -v -e Linux -e BSD )
 
 CC  = gcc
 AS  = yasm
@@ -51,7 +53,7 @@ DEBUG_yasm = -g dwarf2
 DEBUG_nasm = -g
 
 # Default arch= build options
-CFLAGS_gcc = -Wall
+CFLAGS_    = -Wall
 ASFLAGS_   = -f elf64
 ARFLAGS_   = cr $@
 STRIP_gcc  = strip -d -R .comment $@
@@ -69,22 +71,18 @@ ARFLAGS_win64 = -out:$@
 # arch=mingw build options
 ASFLAGS_mingw = -f win64
 ARFLAGS_mingw = cr $@
-lsrcmingw = $(lsrc)
-unit_testsmingw = $(unit_tests)
-examplesmingw = $(examples)
-perf_testsmingw = $(perf_tests)
+LDFLAGS_mingw = -Wl,--force-exe-suffix
 
 LDFLAGS_so = -Wl,-soname,$(soname)
 
 ifeq ($(arch),mingw)
   CC=x86_64-w64-mingw32-gcc
   AR=x86_64-w64-mingw32-ar
-  LDFLAGS = -Wl,--force-exe-suffix
 endif
 
-ifeq ($(shell uname),Darwin)
-  ASFLAGS_   = -f macho64 --prefix=_
-  ARFLAGS_   = -r $@
+ASFLAGS_Darwin = -f macho64 --prefix=_
+ARFLAGS_Darwin = -r $@
+ifeq ($(arch),Darwin)
   LDFLAGS_so =
   STRIP_gcc  =
 endif
@@ -95,8 +93,9 @@ ASFLAGS  = $(ASFLAGS_$(arch)) $(ASFLAGS_$(CC)) $(DEBUG_$(AS)) $(DEFINES) $(INCLU
 ARFLAGS  = $(ARFLAGS_$(arch))
 DEFINES += $(addprefix -D , $D)
 
+lsrc += $(lsrc_$(host_cpu))
 O = bin
-lobj  += $(patsubst %.c,%.o,$(patsubst %.asm,%.o,$(lsrc$(arch)) $(lsrc_intrinsic)))
+lobj  += $(patsubst %.c,%.o,$(patsubst %.asm,%.o,$(lsrc) $(lsrc_intrinsic)))
 objs  = $(addprefix $(O)/,$(notdir $(lobj)))
 
 
@@ -117,20 +116,20 @@ exampleswin64 = $(examples)
 perf_testswin64 = $(perf_tests)
 
 # Build and run unit tests, performance tests, etc.
-all_tests = $(notdir $(sort $(perf_tests$(arch)) $(check_tests$(arch)) $(unit_tests$(arch)) $(examples$(arch)) $(other_tests)))
-all_unit_tests = $(notdir $(sort $(check_tests$(arch)) $(unit_tests$(arch))))
-all_perf_tests = $(notdir $(sort $(perf_tests$(arch))))
-all_check_tests = $(notdir $(sort $(check_tests$(arch))))
+all_tests = $(notdir $(sort $(perf_tests) $(check_tests) $(unit_tests) $(examples) $(other_tests)))
+all_unit_tests = $(notdir $(sort $(check_tests) $(unit_tests)))
+all_perf_tests = $(notdir $(sort $(perf_tests)))
+all_check_tests = $(notdir $(sort $(check_tests)))
 
 $(all_unit_tests): % : %.c $(lib_name)
 $(all_perf_tests): % : %.c $(lib_name)
-$(sort $(notdir $(examples$(arch)))): % : %.c $(lib_name)
+$(sort $(notdir $(examples))): % : %.c $(lib_name)
 $(sort $(notdir $(other_tests))): % : %.c $(lib_name)
 
 sim test trace: $(addsuffix .run,$(all_unit_tests))
 perf: $(addsuffix .run,$(all_perf_tests))
 check: $(addsuffix .run,$(all_check_tests))
-ex:   $(notdir $(examples$(arch)))
+ex:   $(notdir $(examples))
 all: lib $(all_tests)
 other: $(notdir $(other_tests))
 tests: $(all_unit_tests)
@@ -150,7 +149,7 @@ $(addsuffix .run,$(all_tests)): %.run : %
 	@echo Completed run: $<
 
 # Other build rules
-msg = $(if $(DEBUG),DEBUG) $(patsubst 32,32-bit,$(arch)) $D
+msg = $(if $(DEBUG),DEBUG) $(patsubst 32,32-bit,$(host_cpu)) $D
 
 $(O)/%.o: %.asm
 	@echo "  ---> Building $< $(msg)"
@@ -190,8 +189,8 @@ so_lib_ver  = $(so_lib_inst).$(version)
 soname      = $(so_lib_inst).$(word 1, $(subst ., ,$(version)))
 
 slib: $(so_lib_name)
-aobjs  += $(addprefix $(O)/,$(patsubst %.asm,%.o,$(filter %.asm,$(notdir $(lsrc$(arch)) $(lsrc_intrinsic)))))
-shared_objs  += $(addprefix $(O)/shared_ver_,$(patsubst %.c,%.o,$(filter %.c,$(notdir $(lsrc$(arch)) $(lsrc_intrinsic)))))
+aobjs  += $(addprefix $(O)/,$(patsubst %.asm,%.o,$(filter %.asm,$(notdir $(lsrc) $(lsrc_intrinsic)))))
+shared_objs  += $(addprefix $(O)/shared_ver_,$(patsubst %.c,%.o,$(filter %.c,$(notdir $(lsrc) $(lsrc_intrinsic)))))
 
 $(O)/shared_ver_%.o: %.c
 	@echo "  ---> Building shared $< $(msg)"