--- configure.ac.dist	2015-12-09 09:10:25.740408191 +0100
+++ configure.ac.dist	2015-12-09 10:30:02.307126162 +0100
@@ -100,23 +100,30 @@ dnl check for getopt in standard library
 dnl AC_CHECK_FUNCS(getopt_long , , [LIBOBJS="$LIBOBJS getopt.o getopt1.o"] )
 AC_CHECK_FUNCS(getopt_long, [], [])
 
-AC_CHECK_SIZEOF(void*,1)
-
 asm_optimisation=no
 case "$host_cpu" in
 	x86_64)
-		if test $ac_cv_sizeof_voidp = 4 ; then
-			# This must be a 32 bit user space running on 64 bit kernel so treat
-			# this as ia32.
-			cpu_ia32=true
-			AC_DEFINE(FLAC__CPU_IA32)
-			AH_TEMPLATE(FLAC__CPU_IA32, [define if building for ia32/i386])
-		else
-			# x86_64 user space and kernel.
-			cpu_x86_64=true
-			AC_DEFINE(FLAC__CPU_X86_64)
-			AH_TEMPLATE(FLAC__CPU_X86_64, [define if building for x86_64])
-			fi
+		AC_COMPILE_IFELSE(
+			AC_LANG_PROGRAM([], [[{
+				#if ( defined __ILP32__ and defined __x86_64__ ) or defined __x86_64__
+				return 0
+				#else
+					#error "neither x32 nor amd64 binary build"
+				#fi
+				}]]
+			), [
+				# This must be a 32 bit user space running on 64 bit kernel so treat
+				# this as ia32.
+				cpu_ia32=true
+				AC_DEFINE(FLAC__CPU_IA32)
+				AH_TEMPLATE(FLAC__CPU_IA32, [define if building for ia32/i386])
+			], [
+				# either x86_64 or x32 user space and kernel.
+				cpu_x86_64=true
+				AC_DEFINE(FLAC__CPU_X86_64)
+				AH_TEMPLATE(FLAC__CPU_X86_64, [define if building for x86_64])
+			]
+		)
 		asm_optimisation=$asm_opt
 		;;
 	i*86)