diff --git a/desmume/src/types.h b/desmume/src/types.h
index 6bf6101a3..9903e2d54 100644
--- a/desmume/src/types.h
+++ b/desmume/src/types.h
@@ -21,17 +21,15 @@
 #define TYPES_HPP
 
 #ifndef FASTCALL
-#ifdef __i386__
+#ifdef __MINGW32__
+#define FASTCALL __attribute__((fastcall))
+#elif defined (__i386__)
 #define FASTCALL __attribute__((regparm(3)))
 #else
 #define FASTCALL
 #endif
 #endif
 
-#ifndef __fastcall
-#define __fastcall FASTCALL
-#endif
-
 #ifndef INLINE
 #ifdef _MSC_VER
 #define INLINE _inline