diff --git a/3rdparty/softfloat3/build/MAME/platform.h b/3rdparty/softfloat3/build/MAME/platform.h
index 441fdc8d05a..96fc81e348e 100644
--- a/3rdparty/softfloat3/build/MAME/platform.h
+++ b/3rdparty/softfloat3/build/MAME/platform.h
@@ -54,21 +54,28 @@ Softfloat 3 MAME modifications
 /*----------------------------------------------------------------------------
 *----------------------------------------------------------------------------*/
 
-// true for GCC and Clang on Intel and ARM, and MSVC on Intel.
-#define SOFTFLOAT_BUILTIN_CLZ 1
+#if defined(_MSC_VER)
 
-#ifdef _MSC_VER
 #define _INC_MALLOC 0
 #include <intrin.h>
 
 // MSVC has __lzcnt16 as well, but opts-GCC.h expects __lzcnt for uint16_t and uint32_t
+#if defined(_M_IX86) || defined(_M_AMD64)
 #define __builtin_clz __lzcnt
+#endif // defined(_M_IX86) || defined(_M_AMD64)
+#if defined(_M_AMD64)
+#define SOFTFLOAT_BUILTIN_CLZ 1
 #define __builtin_clzll __lzcnt64
-#else
+#endif // defined(_M_AMD64)
+
+#else // defined(_MSC_VER)
+
+// true for GCC and Clang on Intel and ARM, and MSVC on Intel.
+#define SOFTFLOAT_BUILTIN_CLZ 1
 #if defined(PTR64)
 #define SOFTFLOAT_INTRINSIC_INT128 1
-#endif
-#endif
+#endif // defined(PTR64)
+
+#endif // defined(_MSC_VER)
 
 #include "opts-GCC.h"
-