fix x86/x64 MSVC build (#487)
diff --git a/src/x86/ffi.c b/src/x86/ffi.c
index c6c7d2b..883cc4a 100644
--- a/src/x86/ffi.c
+++ b/src/x86/ffi.c
@@ -29,7 +29,7 @@
DEALINGS IN THE SOFTWARE.
----------------------------------------------------------------------- */
-#ifdef __i386__
+#if defined(__i386__) || defined(_M_IX86)
#include <ffi.h>
#include <ffi_common.h>
#include <stdint.h>
diff --git a/src/x86/ffiw64.c b/src/x86/ffiw64.c
index ca4d3ca..b68f69c 100644
--- a/src/x86/ffiw64.c
+++ b/src/x86/ffiw64.c
@@ -25,7 +25,7 @@
DEALINGS IN THE SOFTWARE.
----------------------------------------------------------------------- */
-#ifdef __x86_64__
+#if defined(__x86_64__) || defined(_M_AMD64)
#include <ffi.h>
#include <ffi_common.h>
#include <stdlib.h>