diff --git a/src/lib/utils/mul128.h b/src/lib/utils/mul128.h
index 8cdaae2..54bb670 100644
--- a/src/lib/utils/mul128.h
+++ b/src/lib/utils/mul128.h
@@ -39,10 +39,15 @@ namespace Botan {
 #elif defined(BOTAN_BUILD_COMPILER_IS_MSVC) && defined(BOTAN_TARGET_CPU_HAS_NATIVE_64BIT)
 
 #include <intrin.h>
-#pragma intrinsic(_umul128)
-
-#define BOTAN_FAST_64X64_MUL(a,b,lo,hi) \
+#if defined(_M_ARM64)
+   #pragma intrinsic(__umulh)
+   #define BOTAN_FAST_64X64_MUL(a,b,lo,hi) \
+   do { *lo = a * b; *hi = __umulh(a, b); } while(0)
+#else
+   #pragma intrinsic(_umul128)
+   #define BOTAN_FAST_64X64_MUL(a,b,lo,hi) \
    do { *lo = _umul128(a, b, hi); } while(0)
+#endif
 
 #elif defined(BOTAN_USE_GCC_INLINE_ASM)